Résumé
The resource-use hypothesis, proposed by E.S. Vrba, states that habitat
fragmentation caused by climatic oscillations would affect particularly
biome specialists (species inhabiting only one biome), which might show
higher speciation and extinction rates than biome generalists. If true,
lineages would accumulate biome-specialist species. This effect would be
particularly exacerbated for biomes located at the periphery of the global
climatic conditions, namely, biomes that have high/low precipitation and
high/low temperature such as rainforest (warm-humid), desert (warm-dry),
steppe (cold-dry), and tundra (cold-humid). Here, we test these hypotheses
in swallowtail butterflies, a clade with more than 570 species, covering
all the continents but Antarctica, and all climatic conditions.
Swallowtail butterflies are among the most studied insects, and they are a
model group for evolutionary biology and ecology studies. Continental
macroecological rules are normally tested using vertebrates, this means
that there are fewer examples exploring terrestrial invertebrate patterns
at global scale. Here, we compiled a large GIS database on swallowtail
butterflies’ distribution maps and used the most complete time-calibrated
phylogeny to quantify diversification rates. In this paper we aim to
answer the following questions: 1) Are there more biome-specialists
swallowtail butterflies than biome-generalists? 2) Is diversification rate
related to biome specialisation? 3) If so, do swallowtail butterflies
inhabiting extreme biomes show higher diversification rates? 4) What is
the effect of species distribution area? Our results showed that
swallowtail family presents a great number of biome specialists which
showed substantially higher diversification rates compared to generalists.
We also found that biome-specialists are unevenly distributed across
biomes. Overall, our results are consistent with the resource-use
hypothesis., species climatic niche and biome fragmentation as key factors
promoting isolation.