Mammal Population Losses and the Extinction Crisis

Ceballos, Gerardo; Ehrlich, Paul R.

doi:10.1126/science.1069349

Cited by 773 publications

(605 citation statements)

References 23 publications

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“…The loss and fragmentation of habitat truncate movement, reduce connectivity, and often precede the decline and extirpation of a species (Ceballos & Ehrlich, 2002;Baguette et al, 2013). In rivers, habitat connectivity is primarily longitudinal and in general confined to the river corridor.…”

Section: Introductionmentioning

confidence: 99%

The impact of a small-scale riverine obstacle on the upstream migration of Atlantic Salmon

et al. 2017

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The behaviour of returning Salmo salar (Linnaeus, 1758) approaching, and attempting to pass low-head weirs remains relatively unknown. A radio telemetry array was created at a low-head weir to enable the behaviour of S. salar (n = 120) to be observed as they approached and attempted to pass the barrier. The majority of fish successfully passed the barrier on their first or second attempt, some individuals required 11 attempts prior to successful passage occurring. Mean delay at the barrier per fish was 47.8 h (±SD 132.0 h), range 15 min to 31 days. Passage success on a fish's initial attempt was significantly predicted by the amount of searching a fish undertook, fork length, and fat content. Fish were more likely to have a successful first passage attempt if it was smaller with a low fat content and exerted a greater effort in searching for a passage channel. Small-scale barriers cause delays and increased energy expenditure in migrating fish. Barriers may be creating an anthropogenic selection pressure for traits which enable passage success. The impact of a delay at a barrier and increased energy expenditure on reproduction and gonad development remains unknown but is likely to be negatively impacted by instream anthropogenic structures.

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Section: Introductionmentioning

confidence: 99%

The impact of a small-scale riverine obstacle on the upstream migration of Atlantic Salmon

et al. 2017

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“…The prevalence of certain threats, such as hunting, compounded by the ecological traits of some species (large body size; low density; large home range size; migratory or nomadic movements), means declines are taking place even in protected areas [12,13] and within the great expanses of tropical wilderness [14,15]. Consequently, many mammals have current ranges dramatically reduced from their historical extent [16][17][18]. For some, the loss has been complete with some 255 species of mammals documented to have gone extinct in the last 10 000 years [19], of which one-third have taken place in the last 500 years [20].…”

Section: Introductionmentioning

confidence: 99%

The changing fates of the world's mammals

Hoffmann

Belant

Chanson

et al. 2011

Phil. Trans. R. Soc. B

174

140

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Al Ain Wildlife Park and Resort, PO Box 45553, Abu Dhabi, United Arab EmiratesA recent complete assessment of the conservation status of 5487 mammal species demonstrated that at least one-fifth are at risk of extinction in the wild. We retrospectively identified genuine changes in extinction risk for mammals between 1996 and 2008 to calculate changes in the International Union for Conservation of Nature (IUCN) Red List Index (RLI). Species-level trends in the conservation status of mammalian diversity reveal that extinction risk in large-bodied species is increasing, and that the rate of deterioration has been most accelerated in the Indomalayan and Australasian realms. Expanding agriculture and hunting have been the main drivers of increased extinction risk in mammals. Site-based protection and management, legislation, and captivebreeding and reintroduction programmes have led to improvements in 24 species. We contextualize these changes, and explain why both deteriorations and improvements may be under-reported. Although this study highlights where conservation actions are leading to improvements, it fails to account for instances where conservation has prevented further deteriorations in the status of the world's mammals. The continued utility of the RLI is dependent on sustained investment to ensure repeated assessments of mammals over time and to facilitate future calculations of the RLI and measurement against global targets.

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“…As a result, populations of many species have become small and greatly isolated (Ceballos and Ehrlich 2002). Typically, such populations are subject to genetic drift and inbreeding with associated decline in fitness due to inbreeding depression (Frankham 1995;Hedrick and Kalinowski 2000).…”

Section: Introductionmentioning

confidence: 99%

Dynamics of genetic rescue in inbred Drosophila melanogaster populations

et al. 2010

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Genetic rescue has been proposed as a management strategy to improve the fitness of genetically eroded populations by alleviating inbreeding depression. We studied the dynamics of genetic rescue in inbred populations of Drosophila. Using balancer chromosomes, we show that the force of heterosis that accompanies genetic rescue is large and allows even a recessive lethal to increase substantially in frequency in the rescued populations, particularly at stress temperatures. This indicates that deleterious alleles present in the immigrants can increase significantly in frequency in the recipient population when they are in linkage disequilibrium with genes responsible for the heterosis. In a second experiment we rescued eight inbred Drosophila populations with immigrants from two other inbred populations and observe: (i) there is a significant increase in viability both 5 and 10 generations after the rescue event, showing that the increase in fitness is not transient but persists long-term. (ii) The lower the fitness of the recipient population the larger the fitness increase. (iii) The increase in fitness depends significantly on the origin of the rescuers. The immigrants used were fixed for a conditional lethal that was mildly deleterious at 25°C but lethal at 29°C. By comparing fitness at 25°C (the temperature during the rescue experiment) and 29°C, we show that the lethal allele reached significant frequencies in most rescued populations, which upon renewed inbreeding became fixed in part of the inbred lines. In conclusion, in addition to the fitness increase genetic rescue can easily result in a substantial increase in the frequency of mildly deleterious alleles carried by the immigrants. This can endanger the rescued population greatly when it undergoes recurrent inbreeding. However, using a sufficient number of immigrants and to accompany the rescue event with the right demographic measures will overcome this problem. As such, genetic rescue still is a viable option to manage genetically eroded populations.

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Mammal Population Losses and the Extinction Crisis

Cited by 773 publications

References 23 publications

The impact of a small-scale riverine obstacle on the upstream migration of Atlantic Salmon

The impact of a small-scale riverine obstacle on the upstream migration of Atlantic Salmon

The changing fates of the world's mammals

Dynamics of genetic rescue in inbred Drosophila melanogaster populations

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