Biodiversity

Monday, March 26, 2007

DESCRIPTION OF Breviceps Poweri

Breviceps poweri Parker,1934 (Power's rain frog)

Female length 50 mm.
Lower surface texture unknown.
Lower surface colour unknown.
Tympanum not visible.
Inner toes unknown.
Outer toes unknown.
Endemism not endemic to South Africa.
Advertisement call whistle.
Call position unknown.
Call frequency 1.5 kHz.
Eye size unknown.
Dorsum colour brown/black.
Dorsum pattern unknown.



date of photo February,2006
location Mughese Forest Reserve (Misuku hills,Malawi)
photographer Vincenzo Mercurio

available at:
http://calphotos.berkeley.edu/browse_imgs/amphibian_sci_8.html
reference:Channing, A (2001) Amphibians of Central and Southern Africa. Cornell University Press, Ithaca, New York. Pp 209-228 ISBN 1 919825 63 0

DESCRIPTION OF SPECIES WITHIN THE GENUS BREVICEPS(8)

Breviceps adspersus Peters,1882 (Common rain frog)

Female length 60 mm.
Lower surface texture smooth.
Lower surface colour light.
Tympanum not visible.
Inner toes as long as wide.
Outer toes as long as wide.
Endemism not endemic to South Africa.
Advertisement call unknown.
Call position underground.
Call frequency 2 kHz.
Eye size unknown.
Dorsum colour unknown.
Dorsum pattern patches/flecks.



date of photo October 19,1995
latitude 32.35290
longitude 29.56160
location Cape Province,Hogsback (SA)
habitat coastal forest
photographer Robert C. Drewes

available at:
http://calphotos.berkeley.edu/browse_imgs/amphibian_sci_8.html

reference:
Channing, A (2001) Amphibians of Central and Southern Africa. Cornell University Press, Ithaca, New York. Pp 209-228 ISBN 1 919825 63 0

DESCRIPTION OF SPECIES WITHIN THE GENUS BREVICEPS(7)

Breviceps namaquensis Power,1926 (Namaqua rain frog)

Female length 45 mm.
Lower surface texture smooth.
Lower surface colour light.
Tympanum unknown.
Inner toes as long as wide.
Outer toes unknown.
Endemism endemic to South Africa.
Advertisement call whistle.
Call position unknown.
Call frequency 1.3–1.5 kHz.
Eye size large.
Dorsum colour brown/black.
Dorsum pattern unknown.



available from:
http://www.houthoop.co.za/Photo_Reptiles.shtml
reference: Channing, A (2001) Amphibians of Central and Southern Africa. Cornell University Press, Ithaca, New York. Pp 209-228 ISBN 1 919825 63 0

NATURE'S INVESTMENTS INTO PAST BIODIVERSITY

Biodiversity can be defined as the number and variability of species, genes and communities, temporally and spatially (Sepkoski 1997). Understanding past biodiversity is important if one wants to understand the evolutionary processes that generated present biodiversity. However, our understanding of biodiversity is strongly influenced by factors such as: completeness of the fossil record, taxonomic accuracy, precision of dating fossils and quality of preservation of these fossils (Sepkoski 1997). In the present essay, past biodiversity and the methods used to reconstruct past biodiversity will be discussed.

Reconstructing the ecological history of the Calamiteans

Wang et al (2006) used fossils and comparative anatomy and morphology to reconstruct various aspects of extinct Calamiteans (a group of gymnosperms). Today, only one extant genus, namely Equisetum spp is known. A permineralized fossil stem of Arthropitys yunnanensis was found in a mine spoil at Housuo Coal Mine, eastern Yunnan Province, southwestern China, preserved in volcaniclastic tuffs. The stem dated back to the upper Permian. The stem was cut into a longitudinal and horizontal section using a rock saw. Subsequently exposed surfaced were prepared by the acetate peel technique using HCl (hydrochloric acid) to notch the carbonate matrix. The fossil stem showed morphological and anatomical features that have subsequently been lost in modern species. From the study they found that A. yunnanensis had a thick secondary xylem with growth rings, which suggests that the species experienced frequent fluctuations in environmental stresses, such as water availability during drought. The lignified secondary xylem of the stem suggested that it had a semi-self supporting habit. Leaf traces arranged in two whorls were found in the cortex. This indicated that A. yunnanensis had oblique to vertical leaves, which is in contrast with the generalization that members of the genus Arthropitys all had horizontal leaves. The study neatly showed how Calamiteans have changed over time and in addition gave some idea of what the general habit during the Upper Permian.

Using the fossil record to reconstruct the history of Ichthyosaurus

In a paper by Martill (1996), the morphology, anatomy and habit of the Ichthyosaurs; extinct marine tetrapods are described based on fossil evidence, dentition and comparative anatomy. These reptilian, but presumably warm-blooded tetrapods were exclusively marine. Hence, the fossil record shows numerous well preserved specimens. These animals are usually preserved in open marine sedimentary rocks, such as clays and shale which is slightly enriched with organic carbon. These organisms first appear in the fossil record in the lower Triassic, at which stage it resembled the crocodilians. Early Jurassic specimens show a change in body form, and resembled primitive dolphins. The fossil record shows temporal changes in dentition amoungst these organisms, which also suggest changes in feeding habits. Specimens have been found in Posidonia Shale of Southern Germany (around the Late Jurassic), that showed soft tissue outlines, stomach contents and even the embryo in the body cavity. From the soft tissue, it was observed that the width and length of the limbs of Early and Late Jurassic forms were greatly enhanced. The latter suggests that these forms had a rapid means of locomotion. When stomach contents were examined, hooklets of belemnites were found, and rarely fish remains (fish remains were only found in juvenile guts). The belemnites were bottom dwelling mollusks and this suggests that the Ichthyosaurs fed in deeper water. In support of the latter idea, specimens such as Ophthalmosaurus of the Early Jurassic had enormous eyes which are thought to have enhanced vision during feeding in deeper dark water. It is thought that Ichthyosaurs underwent a transition from surface piscivory to deeper water molluscivory during its life cycle. Like other oceanic sea breather, the bone of Ichthyosaurs was spongy as a way of reducing its body density. From fossil evidence of these animals, we can witness changes in body forms over evolutionary time as well as reconstruct the way in which they lived.





Figure 1: Middle Triassic-Late Cretaceous fossil Ichthyosuarus
http://en.wikipedia.org/wiki/Image:Fishchsaurier-fg01.jpg

Using gall in Psaronius fronds to reconstruct the ecological history of Holometabola

Labandeira and Philips (1996) tried to reconstruct the ecological history of Holometabola from fossil Psaronius tree-fern fronds found from the Upper Pennsylvanian Mattoon Formation of Illinois Basin. The occurrence of insect herbivory during the Late Carboniferous has been questioned, and in the study done by Labandeira and Philips (1996) they suggest that modern insect herbivore types were essentially established in Late Pennsylvanian coal swamp forests. Fossil galls were found in the fronds of Psaronius, and were observed as abnormally-looking parenchyma tissue surrounded by nutritive tissue. The accumulation of this nutritive tissue is the host plants response to endophagous herbivory. The central lumen of the gall was filled with frass (including undigested ground tissue and fecal pellets). The presence of these large, barrel-shaped, solid fecal pellets with fractured ends was evidence that the endophague was a Holometabolan larva. They further suggest that the Holometabolan larva displayed host and tissue specificity (Labandeira and Phillips 1996).





Figure 2: a) Psaronius tree fern, 7 m tall and host of the earliest known plant gall b) Fronds of fossil Psaronius containing gall ca= undigested frass, co=coprolite, lu=gall lumen, nt=nutritive tissue, pa=unmodified parenchyma, vt= vascular tissue.
Labandeira and Philips (1996)

Fossils in Amber

Amber is a form of fossilized tree resin, which has been known to trap various small invertebrates such as insects, spiders and other terrestrial arthropods. Amber fossils provide detailed morphological comparisons with extant relatives of extinct taxa. Arthropods in Amber are known to provide information on past biogeographical distributions and serves as a good indicator of past climatic regimes. Syninclusions (where more than one specimen is entrapped in the resin) provide valuable information on the interaction between organisms (for example: predation, maternal care, mating, parasitism etc.). Further more, the rapid mode of fixation and dehydration during amber formation, may be sufficient to preserve DNA. The latter idea has been questioned, but is more likely than finding DNA in any other fossil type (Penny 2006).



Figure 3: Winged ants in Dominican amber. Formed in a tropical climate, typically 16 million years old. Penny (1996)

Invertebrates are usually poorly represented in the fossil record. However, Sutton et al (2001), show yet another way in which soft-bodied invertebrates can be preserved over geological time. Soft bodied organisms that dominate the Silurian Herefordshire fauna of England were fossilized as three dimensional calcitic fossils within spherical to sub-elliptic calcareous nodules. Here, serial grinding and digital photographic techniques were used to capture three- dimensional morphological information. Serial grinding involves the sequential removal of material via abrasion, from a single planar surface, which is subsequently photographed at each stage (Sutton et al. 2001).

Fossils do not only provide knowledge on past biodiversity, but also on the environments in which extinct taxa lived. Various techniques exist on how to effectively process fossils to yield the highest possible resolution. However the techniques used depend on the fossilized organism and the substrate.

References

http://en.wikipedia.org/wiki/Image:Fischsaurier_fg01.jpg

Labandeira C, Phillips T (1996) A Carboniferous insect gall: Insight into early ecologic history of the Holometabola. Proceedings of the National Academy of Science of the United States of America 93: 8470-8474

Martill D (1996) Fossils explained 17: Ichthyosaurs. Geology Today 194-196

Penny D (2006) Fossils in Amber: Unlocking the secrets of the past. Biologist 53(5): 247-251

Sepkoski J (1997) Biodiversity: Past, Present, and Future. Journal of Paleontology 71 (4) 533-539

Sutton M, Biggs D, Siveter D 1, Siveter D 2 (2001) Methodologies for the Visualization and Reconstruction of three-dimensional fossils from the Silurian Herefordshire Lagerstatte. Palaeontologia Electronica 4 (1): 1-17

Wang S, Hilton J, Galtier J, Tian B (2006) A large anatomically preserved calamitean stem from the Upper Permian of southwest China and its implications for calamitean development and functional anatomy. Plant Systematics and Evolution 261: 229-244

DESCRIPTION OF SPECIES WITHIN THE GENUS BREVICEPS(7)

Breviceps montanus Power,1926 (Mountain rain frog)

Female length 52 mm.
Lower surface texture rough/granular.
Lower surface colour dark.
Tympanum not visible.
Inner toes as long as wide.
Outer toes as long as wide.
Endemism unknown.
Advertisement call whistle.
Call position unknown.
Call frequency 2.2 kHz.
Eye size unknown.
Dorsum colour unknown.
Dorsum pattern vertebral stripe.



date of photo June,1999
photo location Stellenbosch,Cape Province (SA)
photographer Robert C. Drewes

available at:
http://calphotos.berkeley.edu/browse_imgs/amphibian_sci_8.html
reference:
Channing, A (2001) Amphibians of Central and Southern Africa. Cornell University Press, Ithaca, New York. Pp 209-228 ISBN 1 919825 63 0

FYNBOS: HERITAGE AT OUR FEET

Cape Floral Kingdom

The Cape Floral Kingdom (CFK) is one of six globally recognized plant kingdoms and occurs in South Africa in the Western Cape Province extending eastwards into the Eastern Cape Province [16]. The Cape Floral Kingdom is the smallest of all six kingdoms and is highly unique as it is the only one fully contained within a single country and is characterized by a high diversity, 8700 plant species, and high endemism, 68% of it’s plant species are confined to this kingdom 90 000km2 large [5]. The CFK consists of the five biomes namely: fynbos, renosterveld, succulent karoo, sub-tropical thicket and afromontane forest [4]. Fynbos is the dominant vegetation of the CFK as 80 percent of the CFK consists of fynbos [8].

Fynbos is evergreen, sclerophyllous shrubland [11] that occurs on nutrient poor soil of the Cape Fold Belt Mountains. It consists of four characteristic growth forms namely proteoids (tall protea shrubs with large leaves), ericoids (heath-like shrub), restiods (reed-like plants) and geophytes (bulbous plants) [4]. The presence of restoid is a distinguishing feature of fynbos as it is always present whereas proteoid and ericoids may be rare and geophytes only appear in winter [8].

Fynbos Biome

There are key biotic and a biotic factors that determine the fynbos distribution, these factors include: summer drought and winter rainfall (mediterranean type climate), low soil nutrients and recurring fire and wind, however, summer drought is a variable component over the South African landscape as it is much more intense in the west than in the east [8]. Biomes are climatically defined but the fynbos biome is not, as the their presence is determined by the absence of nutrients in soils on which they occur [12]. Quartzites and sandstones yield infertile soils whereas the softer shales are more fertile [8]. Fire is a “keystone factor in the long term survival of fynbos” as it plays a major role in its cycle of “destruction, regeneration, maturation and destruction again” [8]. Fire has placed a selective pressure over fynbos and in response small animals and plants have evolved in order to survive. It is not just the physical characteristics of the fire that has such a major influence on fynbos but the complex fire regime i.e. the time lapse between fires, the season in which it burns and the intensity and area it covers [8].

The Origin of Fynbos

Approximately 65 million years ago the present fynbos region was covered with tropical vegetation, ancestral fynbos forms included representatives from the: Proteaceae, Ericaceae and Restionaceae families and were restricted to mountainous areas [8]. Mountains were built of erosion- resistant sandstone that resulted in nutrient poor soils that could have supported heath land-like vegetation [10]. Some CFR palaeoendemics from this era seem to have survived through shelters provided by mountain peaks capturing moisture [14].


About 35 million years ago the climate transformed into a drier and colder type, allowing a form of woodland to occur, this dry period was brought to an end again by the return of a warm moist-tropical period [8]. Then approximately 20 million years ago one of the most historical events in the origin of fynbos occurred, the development of the cold cicum-Antarctic current [8].



This resulted in the complete glaciations of Antarctica approximately 10 million years ago and the formation of the cold Benguela current that ran along the South-Western coast of Africa (Figure 1) [10]. These conditions caused the Mediterranean climatic system typical of the fynbos region as summer-rainfall got blocked off leaving only winter rain [10]. This climatic system was not in favour to the present tropical flora that inevitably became extinct leaving open habitats that the mountainous heath vegetation then occupied [10]. Modern species then radiated from these ancestral lineages, the aridification of the region together with the increase in the fire occurrence played pivotal roles in fynbos diversification [8].


Figure 1:A timeline showing changes in the species diversity and the proportion of area occupied by modern fynbos species [10].

Evolution of Fynbos

This level of endemism observed amongst fynbos vegetation is typically found on islands and is due to the particular geology and geomorphologic evolution of this area: sandy, nutrient poor, acid soils from sandstone and quartzite of the Table Mountain and Wittenberg Groups form the mountains of the Cape Folded Belt tend to be rich in endemism by promotion of speciation [14]. The rugged mountains provided multiple combinations of aspect, substrate and altitude and therefore a vast array of niches for plants to occupy therefore promoting species diversification through niche specialization. Another observation is that the particular location and orientation of the Cape Mountains at the southern tip of Africa favoured speciation as it cut off gene flow from surrounding areas therefore maintaining a “distinct floristic identity” [14].

Adaptations of Fynbos

One important adaptation of fynbos is the high incidence of schlerophylly [12], schlerophyllous plants are hard as they contain ligin that allows plants to resist dry conditions by preventing wilting. Lignin also allows these plants to grow in phosphorus deficient soils (a major nutrient nutrients scarce in the soils) even when phosphorous is lacking for substantial cell growth. In fire-prone ecosystems many plants possess traits that increase their flammability, scherophylly aids in flammability of the vegetation, essential to fynbos as fire is an integral ecosystem process [13].

As mentioned earlier, fire is a major ecological and selective agent in this vegetation as a correct fire regime plays an integral part in fynbos plants and their future generations [7]. Fynbos have adapted to fire by becoming reseeders, which complete their life cycle within a time period and produce seeds (normally fire-protected), or as resprouters [7].

Many fynbos species have established specialized root systems in order to adapt to poor nutrient soil status; root systems include: proteoid roots and versicular arbuscular mycorrhizal root systems [3]. Adaptations of roots have been observed in fynbos plant species, namely mycorrhizal infected and proteoid (cluster) roots. These nutrient aquiring adaptations increase species diversity in the Fynbos biome by promoting co-existence of mycorrhizal and non-mycorrhizal families [1].

Mycorrhiza is a form of mutualism between roots and soil fungi and two forms exits namely: ectomycorrhizde and endomycorhizzae, the hypae of endomycprrhizae develop extensively within the cortical cells of host roots; vesicular-arbuscular mycorrhiza (VAM) is a form of endomycorhizzae and 62% of flora found with the CFK form VAM [1]. Endomycorrhizas have been found in abundance in certain fynbos plants namely in Ericaceae species [8]. Members of the Rosidae family also possess VAM [3].

Proteaceae and Restionaceae are perennial families that dominate in older fynbos vegetation and contribute a large biomass that does not form mycorrhizal roots but develop proteoid roots (Figure 2) [2]. Most members of the Proteacea family are able to survive and flourish on substrates, typical to that of fynbos, indicating proteoid roots are also a highly effective mechanism for metabolic absorption [15].



Figure 2:A proteoid root formation on a protea plant, also named cluster roots for its obvious appearance [6].

Numerous pollination adaptations have also been observed in the fynbos area but special mention has to made about the Ericaceae family that have the most astonishing display of floral attractions [8]. Ericas are highly adapted to their specific pollinators and attractions come in the form of many visual and olfactory cues.

Adaptations to two ecological drivers namely: soils with a low nutrient status and fire are clearly evident in the Fynbos biome. Fynbos’ extremely high diversity and endemism emphasises its success. Root, fire and pollination adapatations are just a few general mechanisms that have allowed Fynbos to become so successful in such a harsh environment.

References:
1. Allsopp N and Stock WD (1993) Mycorrhizal status of plants growing in the Cape Floristic Region, South Africa. Bothalia 23(1): 91-104


2. Allsopp N and Stock WD (1994) VA mycorrhizal infection in relation to edaphic characteristics and disturbances regime in three lowland plant communities in the South-Western Cape, South Africa. Journal of Ecology 82:271-279

3. Allsopp N and Stock WD (1995) Relationship between seed reserves, seedling growth and mycorrhizal responses in 14 related shrubs (Rosidae) from a low nutrient environment. Functional Ecology 9:248-254

4. Anon. Cape Floral Kingdom [Internet]. [Cited 2007 Mar 23] Avaliable from:
http://www.oceansafrica.com/floralkingdom.htm

5. Anon. Fynbos Biome [Internet]. [Cited 2007 Mar 23] Avaliable from:
http://www.plantzafrica.com/vegetation/fynbos.htm

6. Anon. Phytogen [Internet]. [Cited 2007 Mar 23] Available from: http://www.plantsci.org.au/Phytogen/PhytApr01.html

7. Barraclough TG (2006) What can phylogenetics tell us about speciation in the cape flora?.Diversity and Distributions 12:21-26

8. Cowling RM and Richardson D (1995) Fynbos:South Africa’s Unique Floral Kingdom.Fernwood Press, Vlaeberg ,pp 21-40;46-49. ISBN 1-874950-10-5

9. HigginsKB,Lamb AJ and Wilgen (1987) Root systems of selected plant species in mesic mountain fynbos in the jonkershoek valley, south-western cape province. South African Journal of Botany 52(3): 249-257

10. Linder HP and Hardy CR (2004) Evolution of the species-rich cape flora. The Royal Society 359:1623-1632

11. Moll EJ, Jarman (1984) Classification of the Term Fynbos. South African Journal of Sicence 80:351-352

12. Moll EJ, Jarman (1984) Is Fynbos a Heathland. South African Journal of Sicence 80:352-354


13. Schwilk DW and Kerr B (2002) Genetic niche-hiking:an alternative explanation for the evolution of flammability.OIKOS 99:431-442

14. van Wyk A and Smith GF (2001) Regions of Floristic Endemism in Southern Africa: A review with emphasis on Succulents. Umdaus Press, Hatfield, South Africa, pp23-25. ISBN 1-919766-20-0

15. Vorster PW and Jooste JH (1986) Potassium and phosphate absorption by exised ordinary abd proteoid roots of the Proteaceae. South African Journal of Botanty 52(4): 277-282

16. Wikipedia Contributors. Cape Floristic Region [Internet]. [Cited 2007 Mar 13] Available from:
http://en.wikipedia.org/wiki/Cape_floristic_region

DESCRIPTION OF SPECIES WITHIN THE GENUS BREVICEPS(6)

Breviceps rosei Power,1926 (Rose's rainfrog)

Female length 36 mm.
Lower surface texture smooth.
Lower surface colour light.
Tympanum not visible.
Inner toes as long as wide.
Outer toes as long as wide.
Endemism endemic to South Africa.
Advertisement call whistle.
Call position above ground.
Call frequency 2.1 kHz.
Eye size unknown.
Dorsum colour brown/black.
Dorsum pattern vertebral stripe.



photographer Alan Channing

available at:
http://www.botany.uwc.ac.za/envfacts/fynbos/fynbos_frogs.htm

Reference: Channing, A (2001) Amphibians of Central and Southern Africa. Cornell University Press, Ithaca, New York. Pp 209-228 ISBN 1 919825 63 0

DESCRIPTION OF SPECIES WITHIN THE GENUS BREVICEPS(5)

Breviceps gibbosus (Giant rain frog)

Female length 60 mm.
Lower surface texture rough/granular.
Lower surface colour light.
Tympanum not visible.
Inner toes as long as wide.
Outer toes unknown.
Endemism endemic to South Africa.
Advertisement call chirp.
Call position underground.
Call frequency 1.1 kHz.
Eye size unknown.
Dorsum colour brown/black.
Dorsum pattern patches/flecks.




date of photo August 10,2002
location Tamboerskloof,Cape Town,Western Province (SA)
camera Olympus OM2N,Zuiko 135mm Macro,-Velvia-
photographer Wolfgang Ochojski
available at:
http://calphotos.berkeley.edu/browse_imgs/amphibian_sci_8.html

DESCRIPTION OF SPECIES WITHIN THE GENUS BREVICEPS(4)

Breviceps fuscus (Black rain frog)

Female length 51 mm.
Lower surface texture smooth.
Lower surface colour dark.
Tympanum not visible.
Inner toes longer than wide.
Outer toes longer than wide.
Endemism endemic to South Africa.
Advertisement call chirp.
Call position above ground.
Call frequency 1.8 kHz.
Eye size small.
Dorsum colour brown/black.
Dorsum pattern no markings.





date of photo 1998
location Big Tree Reserve (SA)
photographer Miguel Vences
available at
http://calphotos.berkeley.edu/browse_imgs/amphibian_sci_8.html

DESCRIPTION OF SPECIES WITHIN THE GENUS BREVICEPS(3)

Breviceps mossambicus (Mozambique rain frog)

Female length 52 mm.
Lower surface texture unknown.
Lower surface colour unknown.
Tympanum unknown.
Inner toes unknown.
Outer toes unknown.
Endemism not endemic to South Africa.
Advertisement call chirp.
Call position ground level.
Call frequency 2.6 kHz.
Eye size unknown.
Dorsum colour unknown.
Dorsum pattern patches/flecks.



Date of photo 1998
location Kwambonambi (SA)
photographer Miguel Vences
available at
http://calphotos.berkeley.edu/browse_imgs/amphibian_sci_8.html

DESCRIPTION OF SPECIES WITHIN THE GENUS BREVICEPS(2)

Breviceps macrops (Desert rain frog)

Female length 50 mm.
Lower surface texture smooth.
Lower surface colour light.
Tympanum not visible.
Inner toes unknown.
Outer toes unknown.
Endemism not endemic to South Africa.
Advertisement call whistle.
Call position unknown.
Call frequency 1.3 kHz.
Eye size large.
Dorsum colour pale/white.
Dorsum pattern unknown.



date of photo November 19,1994
latitude 29.16930
longitude 16.52800
location ca. 1km near McDougall's
bay campsite (SA)
habitat beach dunes
photographer Robert C. Drewes
available at
http://calphotos.berkeley.edu/browse_imgs/amphibian_sci_8.html

A DESCRIPTION OF THE SPECIES WITHIN THE GENUS BREVICEPS

Breviceps acutirostris (Strawberry Rain Frog)

Female length 40 mm.
Lower surface texture rough/granular.
Lower surface colour unknown.
Tympanum not visible.
Inner toes longer than wide.
Outer toes longer than wide.
Endemism endemic to South Africa.
Advertisement call whistle.
Call position ground level.
Call frequency 1.9 kHz.
Eye size unknown.
Dorsum colour unknown.
Dorsum pattern unknown.




date of photo July 4,2005
location Rochelle Nature Reserve near Franschhoek (SA)
camera Nikon coolpix 990
photographer Arie van der Meijden
available at

http://calphotos.berkeley.edu/browse_imgs/amphibian_sci_8.html

FOSSILS:OUR BRIDGE TO THE PAST

Biodiversity changes not only spatially, but also temporally [7]. This change can be measured, on numerous levels, by the number and variability of: genes, species and ecosystems [7]. Paleontological data is therefore essential for us to comprehend how biodiversity, through evolutionary processes, was generated and changed temporally [7]. Fossil records remain the integral key to reconstructing past biodiversity and are essential to gaining a historical viewpoint of the current “biodiversity crisis” i.e. sixth extinction [8] conservationists are becoming increasingly aware of.
Evolution is the driving force behind biodiversity, but this process occurs over millions of years and many taxa have become extinct over time. Fossil records are essential in reconstruction of biodiversity because not only do they allow paleontologists to study extinct taxa but also these taxa’s morphological and anatomical adaptations that developed through evolution but is now lost in extant forms of those taxa [10].

One of the most detailed fossil records is that of the vertebrate fossil group: Ichthyosaurs [6]. Fossil records indicate that ichthyosaurs originated during the upper part of the Lower Triassic but by the end of the Triassic had become highly diverse and enjoyed a global distribution [6] indicating the success of this group of vertebrates. The fossil record of ichthyosaurs emphasize the importance of this paleontological data as changes in morphological features were observed in specimens (during the early Jurassic) indicating the evolution of these animals to a more efficient aquatic body shape i.e. rear limbs became shorter, physically more powerful shoulder girdle and the caudal section of the vertebral column bent downwards [6]. Some amazing fossil specimens have the soft-tissue outline preserved (Figure 1); more detail and therefore more information could be derived from these records. A dorsal fin, a lunate caudal fin (tail) and forelimbs extending from their skeleton were observed in these unique specimens. Paleontologists could therefore derive that ichthyosaurs from this era used these adaptations to move fast within their aquatic environments, for example the lunate tail would be used for thrusting the animal foreward and the elongated forelimbs would be used for, “underwater flight”[6]. Even more of an exciting discovery was that some, very rare, ichthyosaurs’ fossil specimens contained preserved integument and could actually be examined to provide further evidence of ichthyosaur’s efficiency i.e. less drag effect in locomotion in their aquatic environments [5]. Fossil records are not only important in understanding how extinct taxa lived but also how they perished, by the middle and late Jurassic a major decrease in ichthyosaur’s diversity was observed and by studying other faunal and floral fossil records deductions can be made as to why this species eventually became extinct.


Figure 1: An Ichthyosaur fossil specimen [5].

New discoveries of fossils are increasingly important as each new discovery leads to a better understanding of biodiversity and a more accurate timeline of how diversity evolved [11]. Fossils are also used to reconstruct past environments and therefore past ecosystems. Comparing fossils of pollen, seeds and fruit with linked fauna, all of which characterize various energy levels within an ecosystem, allow the ecosystems where mammoths once lived during different stages of the Pleistocene to be reconstructed [3]. By studying the fossils of fish, microbes, pollen, plants, molluscs and invertebrates a reconstruction of the Connecticut River Valley, in its state between 135 and 225 million years ago, was possible [1]. Ichnofossils (from invertebrates) also play an important role in reconstructing past ecosystems, as they are the result of organism-substrate interactions eg. burrowing and therefore provide information on both morphological and behavioral characteristics [4] Paleosols (soil) result from interactions of different organisms with different types of substrates, paleosols together with ichnofossils proved traces of numerous extinct fauna and flora. These traces are indicators of many physical characteristics in the past environment i.e. temperature, precipitation, water chemistry, levels of oxygen even the water table level at the time all of which add to a more defined reconstructed ecosystem [4].

There are many techniques used to reconstruct biodiversity using fossil specimens. One technique uses peels of coal balls (Figure 2), coal balls are solid masses made up of majority of calcium carbonate that precipitated in ancient peat beds [2]. A large proportion of the anatomical structure of plants, which lived in these ancient coal swamps consisting of peat, was therefore preserved [2]. Coal balls are cut with a saw, producing longitudinal and transverse sections; uncovered surfaces are then etched with hydrochloric acid [10]. A sheet of cellulose acetate, with acetone, is then applied to the exposed surface, which implants fossil cell walls to the sheet, once dried the peel is removed and studied under a microscope [2]. Another technique that uses acid is the analysis of preserved sores and pollen of different plant species. The shale in which some pollen and spore fossils are preserved can be dissolved in acid, thereby exposing the small structures for further study [1].


Figure 2: Above are examples of prepared coal ball peels used in the reconstruction of a 305 million old Carboniferous coal swamp [2]

Another interesting technique used on fossils is called slice data acquisition, used to produce three-dimensional images of fossils [9]. Three-dimensional images are highly informative, as they capture morphological information not possible with the conventional two-dimensional images. There are two approaches to this technique, namely the non-destructive and destructive approach. Non-destructive approaches include: Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) whereas destructive approaches include: serial slicing and serial grinding [9].

Without fossils we would not be able to put together the many puzzle pieces biodiversity has left for us over the past millions of years, so much information on how life operates and its driving force would be lost. Biodiversity, as mentioned above, at present is in a state of crisis and if we ever have a hope of comprehending this situation, and the consequences it will have to life on earth, we have to look back to the past. We have to look to fossils.

References:
1. Abrams J, Riley e (2002) A Reconstruction of the Biodiversity of the Connecticut River Valley Using Fossil and Geological Evidence. The Traprock 1:18-22
2. Anon. Reconstructing an ancient environment. [Online]. [Cited 2007 Mar 13] Available from: www.nmnh.si.edu/paleo/PaleoArt/Techniques/pages/reconstuct9.htm
3. Borodin AV, Strukova TV, Trofimova SS, Zinoviev EV. Reconstruction of mammoth environments at different stages of the Pleistocene in the West-Siberian Plain. [Intenet]. [Cited 2007 Mar 13] Available from: www.cq.rm.cnr.it/elephants2001/pdf/267_271.pdf
4. Hasiotis ST, Dubiel RF, Demko TM. A Holistic Approach to Reconstructing Triassic Paleoecosystems:Using Ichnofossils and Paleosols as a Basic Framework. [Internet]. [Cited 2007 Mar 13] Availablr from: www.nature.nps.gov/geology/paleontology/pub/grd3_3/pefo2.htm
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PHYLICA DESCRIPTIONS

Phylica red
Flowers Red.
Ovary superior.
Interfloral glands 2 number.
Flower sizw 6 mm.
Plant height 120–190 mm.















Phylica orange
Flowers Orange.
Ovary semi-inferior.
Interfloral glands 6 number.
Flower sizw 80 mm.
Plant height 100–350 mm.










Phylica large
Flowers Blue.
Ovary superior.
Interfloral glands 1 number.
Flower sizw 20–30 mm.
Plant height 2000–3000 mm.











Phylica small
Flowers Red.
Ovary inferior.
Interfloral glands 5 number.
Flower sizw 10 mm.
Plant height 150–200 mm.











Phylica blue
Flowers Blue.
Ovary semi-inferior.
Interfloral glands 1 number.
Flower sizw 10 mm.
Plant height 300–600 mm.












Phylica prostrate
Flowers Yellow.
Ovary superior.
Interfloral glands 5 number.
Flower sizw 50 mm.
Plant height 300–400 mm.

PHYLICA TRIVIAL CLASSIFICATION

Key 5a. Phylica characters


Characters: 5 in data, 2 included, 2 in key.
Items: 6 in
data, 6 included, 6 in key.
Parameters: Rbase = 1.40 Abase = 2.00
Reuse = 1.01 Varywt = .80
Characters included: 1–2

Character reliabilities: 1–5,5.0

1(0).
  • Flowers Blue
    ... 2
  • Flowers Orange... Phylica
    orange

  • Flowers Yellow... Phylica prostrate

  • Flowers Red... 3

2(1).

  • Ovary semi-inferior ... Phylica blue

  • Ovary superior... Phylica large

3(1).

  • Ovary inferior ... Phylica small

  • Ovary superior... Phylica red