Up in the air: threats to Afromontane biodiversity from climate change and habitat loss revealed by genetic monitoring of the Ethiopian Highlands bat

Whilst climate change is recognised as a major future
threat to biodiversity, most species are currently threatened by extensive
human-induced habitat loss, fragmentation and
degradation. Tropical high altitude alpine and montane forest
ecosystems and their biodiversity are particularly sensitive to
temperature increases under climate change, but they are also subject to
accelerated pressures from land conversion and degradation due to a
growing human population. We studied the combined effects of anthropogenic
land-use change, past and future climate changes and mountain range
isolation on the endemic Ethiopian Highlands long-eared
bat, Plecotus balensis, an understudied bat that is restricted to
the remnant natural high altitude Afroalpine and Afromontane habitats. We
integrated ecological niche modelling, landscape genetics and
model-based inference to assess the genetic, geographic and
demographic impacts of past and recent environmental changes. We show that
mountain range isolation and historic climates shaped population structure
and patterns of genetic variation, but recent anthropogenic land-use
change and habitat degradation are associated with a severe population
decline and loss of genetic diversity. Models predict that the suitable
niche of this bat has been progressively shrinking since the last
glaciation period. This study highlights threats to Afroalpine
and Afromontane biodiversity, squeezed to higher altitudes under
climate change while losing genetic diversity and suffering population
declines due to anthropogenic land-use change. We conclude that the
conservation of tropical montane biodiversity requires a holistic
approach, using genetic, ecological and geographic information to
understand the effects of environmental changes across temporal scales and
simultaneously addressing the impacts of multiple threats.