Is there evidence of shifting baseline syndrome in environmental managers? An assessment using perceptions of bird population targets in UK nature reserves.

Shifting baseline syndrome (SBS) describes changing perceptions of biological conditions due to a loss of historical knowledge. Perceptions of 'normal' environmental conditions are continually updated, leading to underestimation of the true magnitude of long-term ecological change and potential setting of unambitious management targets. There has been speculation as to the presence and impacts of SBS within conservation management since Daniel Pauly's seminal paper in 1995, which outlined the potential effects of SBS on target-setting in fisheries management. Previous case studies have suggested that SBS may not occur in management, despite empirical evidence of SBS in other systems. In this study, 44 professionals and volunteers involved in bird species management, monitoring and target-setting across England were interviewed. Interviews asked for personal perceptions of current, maximum and target abundance, long-term trends, and perceived conservation priority for six bird species. Using paired tests, this study found no significant effect of experience on perceptions of current, maximum or target abundance of all species, despite differences in national abundance and trends, and differences in participant experience. Further power analysis indicated that even if SBS was statistically detectible with a larger sample, the practical implications of the syndrome would be minimal due to small effect sizes. Finally, the effect of experience on individual perceptions of species conservation priority varied between species, with generational amnesia in the form of 'lifting baselines' suggested for only one of the six species. This study suggests that shifting baseline syndrome may not be as significant a threat in conservation management as first thought.

Assessing current genetic status of the Hainan gibbon using historical and demographic baselines: implications for conservation management of species of extreme rarity.

Evidence-based conservation planning is crucial for informing management decisions for species of extreme rarity, but collection of robust data on genetic status or other parameters can be extremely challenging for such species. The Hainan gibbon, possibly the world's rarest mammal, consists of a single population of ~25 individuals restricted to one protected area on Hainan Island, China, and has persisted for over 30 years at exceptionally low population size. Analysis of genotypes at 11 microsatellite loci from faecal samples for 36% of the current global population and tissue samples from 62% of existing historical museum specimens demonstrates limited current genetic diversity (Na = 2.27, Ar = 2.24, He  = 0.43); diversity has declined since the 19th century and even further within the last 30 years, representing declines of ~30% from historical levels (Na = 3.36, Ar = 3.29, He  = 0.63). Significant differentiation is seen between current and historical samples (FST  = 0.156, P = 0.0315), and the current population exhibits extremely small Ne (current Ne  = 2.16). There is evidence for both a recent population bottleneck and an earlier bottleneck, with population size already reasonably low by the late 19th century (historical Ne  = 1162.96). Individuals in the current population are related at the level of half- to full-siblings between social groups, and full-siblings or parent-offspring within a social group, suggesting that inbreeding is likely to increase in the future. The species' current reduced genetic diversity must be considered during conservation planning, particularly for expectations of likely population recovery, indicating that intensive, carefully planned management is essential.

Using ecological niche modelling to predict spatial and temporal distribution patterns in Chinese gibbons: lessons from the present and the past.

Ecological niche modelling (ENM) is used to predict species' tolerance to changing environmental conditions. Understanding changes in the spatial distribution of species across time is essential in order to develop effective conservation strategies. Here we map the past and present distribution of gibbons across China, a country experiencing extensive anthropogenic habitat destruction and ongoing biodiversity loss. The distribution of gibbons across three time intervals is described based on fossil, historical and modern-day data, and ENM, implemented using DIVA-GIS, is used to predict how modern-day gibbon distributions might respond to future climate change. Predictions based on modern-day data alone fail to reveal patterns of environmental tolerance and geographical distribution shown by gibbons in the relatively recent historical period, emphasizing the need to incorporate past as well as present data in conservation analyses.

How the past impacts the future: modelling the performance of evolutionarily distinct mammals through time.

How does past evolutionary performance impact future evolutionary performance? This is an important question not just for macroevolutionary biologists who wish to chart the phenomena that describe deep-time changes in biodiversity but also for conservation biologists, as evolutionarily distinct species-which may be deemed 'low-performing' in our current era-are increasingly the focus of conservation efforts. Contrasting hypotheses exist to account for the history and future of evolutionarily distinct species: on the one hand, they may be relicts of large radiations, potentially 'doomed' to extinction; or they may be slow-evolving, 'living fossils', likely neither to speciate nor go extinct; or they may be seeds of future radiations. Here, we attempt to test these hypotheses in Mammalia by combining a molecular phylogenetic supertree with fossil record occurrences and measuring change in evolutionary distinctness (ED) at different time slices. With these time slices, we modelled future ED as a function of past ED. We find that past evolutionary performance does indeed have an impact on future evolutionary performance: the most evolutionarily isolated clades tend to become more evolutionarily distinct with time, indicating that low-performing clades tend to remain low-performing throughout their evolutionary history. This article is part of a discussion meeting issue 'The past is a foreign country: how much can the fossil record actually inform conservation?'

Late Holocene extinction of Puerto Rican native land mammals.

West Indian land mammals have suffered the most severe extinctions of any Holocene mammal faunas. However, 'last-occurrence' dates based on radiometric or robust stratigraphic data remain unavailable for most West Indian species, making it impossible to identify factors responsible for these extinctions. Here, we present new radiometric dates from archaeological and palaeontological sites on Puerto Rico, the only Greater Antillean island to have lost all native land mammals. Although it has been suggested that these species died out earlier than other West Indian mammals, we demonstrate that Puerto Rican mammal last-occurrence dates are in close agreement with those from other Antillean islands, as several species in fact persisted for millennia following Amerindian arrival. Echimyid rodents and nesophontid 'island-shrews' were still present on Puerto Rico approximately 1000 years BP, and probably became extinct following European arrival. The large (13kg) heptaxodontid rodent Elasmodontomys obliquus also appears to have survived for over 2000 years after Amerindian colonization, suggesting that at least some large West Indian mammals became extinct in protracted pre-European 'sitzkrieg'-style events rather than 'blitzkrieg'-style overkill.

Modelling the extinction of Steller's sea cow.

Steller's sea cow, a giant sirenian discovered in 1741 and extinct by 1768, is one of the few megafaunal mammal species to have died out during the historical period. The species is traditionally considered to have been exterminated by 'blitzkrieg'-style direct overharvesting for food, but it has also been proposed that its extinction resulted from a sea urchin population explosion triggered by extirpation of local sea otter populations that eliminated the shallow-water kelps on which sea cows fed. Hunting records from eighteenth century Russian expeditions to the Commander Islands, in conjunction with life-history data extrapolated from dugongs, permit modelling of sea cow extinction dynamics. Sea cows were massively and wastefully overexploited, being hunted at over seven times the sustainable limit, and suggesting that the initial Bering Island sea cow population must have been higher than suggested by previous researchers to allow the species to survive even until 1768. Environmental changes caused by sea otter declines are unlikely to have contributed to this extinction event. This indicates that megafaunal extinctions can be effected by small bands of hunters using pre-industrial technologies, and highlights the catastrophic impact of wastefulness when overexploiting resources mistakenly perceived as 'infinite'.