The Paucity of Frugivores in Madagascar May Not Be Due to Unpredictable Temperatures or Fruit Resources

<div><p>The evolution of ecological idiosyncrasies in Madagascar has often been attributed to selective pressures stemming from extreme unpredictability in climate and resource availability compared to other tropical areas. With the exception of rainfall, few studies have investigated these assumptions. To assess the hypothesis that Madagascar’s paucity of frugivores is due to unreliability in fruiting resources, we use statistical modeling to analyze phenology datasets and their environmental correlates from two tropical wet forests, the Réserve Naturelle Intégrale Betampona in Madagascar, and Kibale National Park in Uganda. At each site we found that temperature is a good environmental predictor of fruit availability. We found no evidence of a significant difference in the predictability of fruit availability between the two sites, although the shorter duration of phenological monitoring at Betampona (two years, versus 15 years at Kibale) limits our ability to infer long-term patterns. Comparisons of long-term temperature data from each site (15 years from Kibale and 14 from Betampona) indicate that temperature is more predictable at Betampona than at Kibale. However, there does appear to be a difference between the two sites in the total fruit availability at any given time, with fruit being generally less abundant at Betampona. Our results appear contrary to the prevailing hypothesis of a selective force imposed by unpredictable resource availability or temperature, and we suggest other possible explanations for Madagascar’s unique biota.</p></div

A comparison of Colwell’s index of predictability <i>(P)</i> of temperature and fruit availability at Kibale and Betampona.

<p><b>(A)</b> Colwell’s constancy (<i>C)</i> versus contingency (<i>M)</i> for 15 years of temperature data at Kibale (filled circle) and Betampona (filled triangle); both have been bootstrapped 100 times (open triangles and circles). <b>(B)</b> Colwell’s constancy (<i>C)</i> versus contingency (<i>M)</i> for 15 years and for two-year intervals of total fruit availability at Kibale (star and filled circles, respectively), and 2-years of fruit availability at Betampona (filled triangle); both have been bootstrapped 100 times (open triangles and circles).</p

Stepwise linear regressions to test for climatological correlates of fruit availability in Betampona, Madagascar (A, B) and Kibale, Uganda (C,D).

<p>Stepwise linear regressions to test for climatological correlates of fruit availability in Betampona, Madagascar (A, B) and Kibale, Uganda (C,D).</p

Colwell’s index of predictability for fruit availability: comparing two year intervals from Kibale, Uganda with two years of data from Betampona, Madagascar.

<p>Colwell’s index of predictability for fruit availability: comparing two year intervals from Kibale, Uganda with two years of data from Betampona, Madagascar.</p

Fruit availability and scarcity at Betampona and Kibale.

<p><b>(A)</b> Total fruit availability at each site. Kibale phenology data are presented in 2-year intervals with black lines; Betampona phenology data are shown in light blue. Periods of fruit scarcity at Betampona <b>(B)</b> and Kibale <b>(C)</b>; dark blue lines indicate 25% of the maximum availability, red lines indicate 10%.</p

Nucleotide alignment for exon 3 of the X-linked opsin gene (Indriidae)

Nucleotide alignment of consensus sequences for exon 3 of the X-linked opsin gene (Plain Text file in FASTA format generated in Geneious). Sequences represent 10 species of Indriidae

Nucleotide alignment for exon 5 of the X-linked opsin gene (Indriidae)

Nucleotide alignment of consensus sequences for exon 5 of the X-linked opsin gene (Plain Text file in FASTA format generated in Geneious). Sequences represent 10 species of Indriidae

Supplementary Materials: Novel opsin gene variation in large-bodied, diurnal lemurs

Details on sample collection and opsin genotypin