Contradicting habitat type-extinction risk relationships between living and fossil amphibians.

Melanie Tietje,Mark-Oliver Rödel

doi:10.1098/rsos.170051

Abstract

Trait analysis has become a crucial tool for assessing the extinction risk of species. While some extinction risk-trait relationships have been often identical between different living taxa, a temporal comparison of fossil taxa with related current taxa was rarely considered. However, we argue that it is important to know if extinction risk-trait relations are constant or changing over time. Herein we investigated the influence of habitat type on the persistence length of amphibian species. Living amphibians are regarded as the most threatened group of terrestrial vertebrates and thus of high interest to conservationists. Species from different habitat types show differences in extinction risk, i.e. species depending on flowing waters being more threatened than those breeding in stagnant sites. After assessing the quality of the available amphibian fossil data, we show that today's habitat type-extinction risk relationship is reversed compared to fossil amphibians, former taxa persisting longer when living in rivers and streams, thus suggesting a change of effect direction of this trait. Neither differences between amphibian orders nor environmentally caused preservation effects could explain this pattern. We argue this change to be most likely a result of anthropogenic influence, which turned a once favourable strategy into a disadvantage.

Highlights

With an increasing number of species being potentially threatened by anthropogenic environmental changes, scientists have been searching for new insights into how to determine the extinction risk of species [1,2,3]
The proportion of living amphibian families with a known fossil record was 33%, which is rather low compared to various groups of invertebrates and fishes
The preservation probability of amphibians based on the duration frequency distribution showed that 33% of the amphibian species and about half of the genera were preserved at least once from one geological stage to the other

Summary

Introduction

With an increasing number of species being potentially threatened by anthropogenic environmental changes, scientists have been searching for new insights into how to determine the extinction risk of species [1,2,3]. (IUCN) for example uses a set of trait categories to assess the risk of species for their Red List, which is a 2 prime guide for conservation strategies [6]. It is of importance to test whether the targeted traits are valid in extinction risk assessments across different species and over longer time scales. Such validation would make the assessment process easier and comparable across a larger number of different taxa. Various examples from living and fossil species revealed geographical range size as a good proxy for extinction risk [8,9,10]

Methods

Results

Discussion

Conclusion