Fundamentals of Conservation Biology. Malcolm L. Hunter, Jr.. Читать онлайн. Newlib. NEWLIB.NET

Автор: Malcolm L. Hunter, Jr.
Издательство: John Wiley & Sons Limited
Серия:
Жанр произведения: Биология
Год издания: 0
isbn: 9781119144175
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a half‐sister with her half‐brother, (b) full sister and brother, and (c) full cousins (different parents but identical grandparents). See the text for an explanation of (a) and (b).

      An Important Caveat

      It must be emphasized that the equations presented in this section provide only estimates of the likely effects of processes that diminish genetic diversity. Exceptions may be fairly common. For example, Indian rhinoceros appear to have retained a high level of genetic diversity despite having passed through a serious bottleneck, perhaps because of high mobility of some individuals and long generation times (Dinerstein and McCracken 1990). The same applies to Chilean blue whales (Torres‐Florez et al. 2014) likely for the same reason: both rhinos and blue whales are long‐lived animals. Similarly, an isolated population of pinyon pine (also very long generation times) retained its genetic diversity over 300 years (Betancourt et al. 1991).

      These may be examples of just a few lucky species that survived a bottleneck; the many other species that did not survive are not around to be studied and reported upon here. Even if there might be some benefits to inbreeding, they might be short‐lived if a bottleneck left the species so genetically uniform that it was ill prepared to adapt to future environmental change. That is a big concern for elephant seals and the Española Island giant tortoise we just discussed.

      The sharing of genes between parents and offspring is not the only mechanism by which information is transmitted from one generation to the next. Among many social animals information also moves among individuals and generations through learning, a process often called cultural transmission. Because changes in behavior can occur much faster than evolution, cultural diversity can be critical for adaptation to new circumstances, including global change, particularly for long‐lived animals.

      Conversely, breakdown of cultural transmission has been a problem for conservationists. For example, golden lion tamarins released into their native habitat have had problems identifying food and predators, information that they would have learned from other tamarins under normal circumstances (Kleiman 1989). Many marine mammals have specific dialects unique to particular locales or even social groups, as in the case of sperm whales (Gero et al. 2016). When populations are broken up and fragmented through over‐exploitation these long‐evolved communication systems also erode. Grazing animals like bighorn sheep and moose can take several generations to build their knowledge of their environment (where to go to find green forage), which poses a significant challenge to reintroducing species to ranges unfamiliar to them (Jesmer et al. 2018).

      Among all species, Homo sapiens has the most complex culture, and maintaining human cultural diversity should also be of some concern to conservation biologists. For example, regions of the globe with the highest levels of biological diversity also host the greatest human language diversity (Sutherland 2003). Notably, the very factors that beget biological diversity, such as isolating mechanisms like mountain ranges, rivers, and islands, also beget cultural and language diversity in humans. Yet the same forces of homogenization that are threatening biological diversity are also threatening human cultural diversity: of the estimated 6000 languages spoken in 2000 some 50–90% may not survive through the twenty‐first century (Crystal 2000).

      ([a] Dominic Sherony/Wikimedia Commons/CC BY‐SA 2.0