A review of extinction in experimental populations

Abstract

Summary 1.Population extinction is a fundamental ecological process. Recent experimental work has begun to test the large body of theory that predicts how demographic, genetic and environmental factors influence extinction risk. We review empirical studies of extinction conducted under controlled laboratory conditions. Our synthesis highlights four findings.First, extinction theory largely considers individual, isolated populations. However, species interactions frequently altered or even reversed the influence of environmental factors on population extinction as compared to single-species conditions, highlighting the need to integrate community ecology into population theory. 2. While most single-species studies qualitatively agree with theoretical predictions, studies are needed that quantitatively compare observed and predicted extinction rates. A quantitative understanding of extinction processes is needed to further advance theory and to predict population extinction resulting from human activities. 3. Many stresses leading to population extinction can be assuaged by migration between subpopulations. However, too much migration increases synchrony between subpopulations and thus increases extinction risk. Research is needed to determine how to strike a balance that maximizes the benefit of migration. 4. Results from laboratory experiments often conflict with field studies. Understanding these inconsistencies is crucial for extending extinction theory to natural populations.

Extinction risk and eco-evolutionary dynamics in a variable environment with increasing frequency of extreme events

“…By increasing the intensity of the Poisson distribution of offspring per reproducing couple from 2 to 3, populations almost never went extinct (electronic supplementary material, figure S12). This result shows how a moderate increase in fecundity may have substantial effects on the survival of populations in highly stochastic environments, as also suggested by theoretical [29] and experimental [58] studies, although trade-offs with survival and other life histories should be considered [59]. This might explain why fecundity is strongly selected under environmental change in long running experimental populations [60,61], although whether this is caused by environmental variation or environmental trend is unclear.…”

The effects of power lines on ungulates and implications for power line routing and rights-of-way management

“…Power lines may influence wildlife through disturbance, clearing of forest habitat under power lines, edge, barrier and corridor effects (Willyard and Tikalsky, 2004;Ball, 2012). Fragmentation by power lines could induce genetic drift, as for roads (Epps et al, 2005, Kuehn et al, 2007, and reduce population productivity and persistence (Griffen and Drake 2008;Haanes et al, 2013). Wide-ranging and mobile species as some ungulates will likely encounter power lines within their home ranges (Tables 1 to 7).…”

Experimental separation of genetic and demographic factors on extinction risk in wild populations

“…The importance of the different mechanisms by which small populations may affect extinction risk has been controversial. Attention has increasingly focused on the effects of genetic factors (Franklin 1980, Barrett and Kohn 1991, Lacy 1997, Frankham 2005, Bouzat 2010, Miller et al 2012, in part because of well-documented effects of inbreeding in captive populations, including those of conservation interest in zoos (Charlesworth and Charlesworth 1987, Lacy 1997, O'Brien 1994, Griffen and Drake 2008, and because rapid improvements in DNA analysis has facilitated assessment of genetic structure in small populations. Some biologists have questioned this emphasis, and suggested that nongenetic factors such as demographic stochasticity and environmental factors that cause small population size have overriding importance in natural populations (Simberloff 1988, Caughley 1994, Caro and Laurenson 1994.…”