Evolution isolierter Teilpopulationen der Laubholz-Säbelschrecke Barbitistes serricauda (FABRICIUS 1798)
| Autor: | Christian Richter |
|---|---|
| Rok vydání: | 2008 |
| Předmět: |
Laubholz-Säbelschrecke
Evolution Teilpopulation 0106 biological sciences education.field_of_study Population fragmentation Habitat fragmentation Ecology Population 010607 zoology Zoology Population genetics Small population size Reproductive isolation Biology 010603 evolutionary biology 01 natural sciences Inbreeding depression education Inbreeding |
| Zdroj: | Biodiversity and Ecology Series ISBN: 9783940344571 |
| DOI: | 10.17875/gup2008-704 |
| Popis: | The central European area populated by the ratite bushcricket Barbitistes serricauda (Fabricius 1798) has been fragmented in Prehistoric times by the settling of the copper beech, which was presumably promoted by man. The specimen with low mobility cannot use the copper beech as a means of nourishment. Therefore populations of this type of bushcricket can only be found in places where the copper beech does not grow. These populations are characterized by an outstanding poverty in regard of the number of individuals – sometimes less than 15 specimen – that remains constant for any length of time. The AFLP-analysis of population genetics shows a value of FST = 0,2486 regarding the distance between populations. There was no obvious connection between genetical and geographic distance. In regard to the gene diversity between populations (hs) a value of 0,2577 (AFLP-Data) has been determined. Additionally a RAPD-analysis was performed, which was equally reliable to the AFLP-method. Filial generations of single populations that were bred under standartized conditions, showed significantly diverse lengths of leg. This indicates processes of differentiation in locally isolated populations, as do the differences in the progress of embryonic development influenced by endogenic factors of maternal origin. The consequences of supposable inbreeding within small populations were estimated by tests evaluating fitness, which disclosed several populations to have a very diverse relative rate of survival. This indicates that some, but not all of the populations live under an heightened threat of extinction, supposedly promoted by limited genetical exchange, since none of the populations examined showed signs of malformation during postembryonic development. Population hybrids bred in the labratory under identical testing conditions, whose parents derived from different subpopulations, indicated a postzygotic isolation developing between several populations. Deliberately bred lines of inbreeds showed no signs of reduced fitness in comparison to control breeds. This strongly suggests that inbreeding depression within small local populations does not necessarily occur. When testing the females' preferences in mate choice it was observed that a majority of females prefer males alien to their own population, even if there was some diversity in the results concerning the different populations. In addition, tests regarding the specific temporal patterns of male calling songs did not indicate prezygotic isolation between populations. The fragmentation of the habitat of Barbitistes serricauda did indeed lead to a drastic restriction of genetical exchange between single populations, but the isolation of local populations also led to processes of diversification within the population in general and generated a large genetical variation within the species, which in turn might result in speciation. Therefore, any fragmentation of habitat may contribute to biodiversity in the long run, even if some populations extinguish locally. Hence a positive evaluation of anthropogenic fragmentation of habitat is possible in some cases, since it may have the same results as processes of a natural, i. e. geologic kind. |
| Databáze: | OpenAIRE |
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