Name: BRUNA DA SILVA FONSECA
Type: PhD thesis
Publication date: 12/03/2019
Advisor:
Name |
Role |
|---|---|
| Albert David Ditchfield | Co-advisor * |
| Yuri Luiz Reis Leite | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| Albert David Ditchfield | Co advisor * |
| Cecília Waichert Monteiro | External Alternate * |
| Elisandra de Almeida Chiquito | Internal Examiner * |
| Joyce Rodrigues do Prado | Internal Alternate * |
| Renato Gregorin | External Examiner * |
| Roberta Paresque | Internal Examiner * |
| Valéria da Cunha Tavares | External Examiner * |
| Yuri Luiz Reis Leite | Advisor * |
Summary: Trachops Gray, 1847 (Chiroptera: Phyllostomidae) is a monotypic carnivorous bat, with only
Trachops cirrhosus (Spix, 1823) currently recognized. There are three subspecies that occupy
a large part of the Neotropical region, occurring from southern Mexico to Nicaragua (T. c.
coffini), from Costa Rica to the southeast and northeast of Brazil (T. c. cirrhosus) and from
southern Brazil to Bolivia (T. c. ehrhardti). Although the genus has an ancient origin, ca. 17
million years ago, fossils of the species are scarce and relatively recent, dating to the Late
Pleistocene and Holocene. Regarding its taxonomy, genetic studies have raised the
hypothesis of cryptic speciation in the genus, but no work integrating different data matrices
has been done to date. The main goal of the present study was to investigate the diversity of
Trachops along its geographic distribution, integrating molecular, morphometric and
ecological analyses, to understand the taxonomy of the genus. I used the General Lineage
species concept and operational criteria based on: 1) monophyly in the molecular phylogenies
based on one nuclear and three mitochondrial markers, morphometric divergence with
analysis of Normal Mixture Models, and ecological niche divergence, through ecological
niche modeling and niche identity test. In addition, Trachops phylogeography was also
revisited using haplotype networks and divergence time estimates to understand the
distribution patterns of genetic lineages. Results show that Trachops should be divided into 2
species: T. ehrhardti, monotypic, and T. cirrhosus, with 2 subspecies (T. c. cirrhosus e T. c.
coffini). The phylogenetic analyses pointed to the existence of 7 geographically structured
lineages with genetic divergences > 5%. Among these, the southern Atlantic Forest lineage
(T. ehrhardti) was the most divergent, separating from its sister group (T. cirrhosus) about 7
million years ago. The coalescent species tree reinforces the idea that these two main lineages
comprise distinct species, although statistical support for T. cirrhosus is relatively low in the
gene tree. Morphometric analyses also point to the existence of 2 forms of Trachops: large
sized and small sized. Although this difference is significant, it is not conspicuous, possibly
due to the large geographic range of T. cirrhosus and, therefore, to the existence of
intermediates. Trachops ehrhardti of the Atlantic Forest and T. c. coffini from Central
America are of similar size, but show morphological differences. Trachops c. cirrhosus is
larger, showing clinal size variation, and Panama seems to be the contact zone with T. c.
coffini. The niche overlap test revealed greater overlap between T. ehrhardti and T. c. coffini,
than between T. ehrhardti and its neighbor T. c. cirrhosus, suggesting that the similarity
between niches may be acting to maintain similarities in size. In addition, the niche identity
test corroborated the uniqueness of the niches for each taxon. Using these results, the genetic,
ecologic, and morphometric distinction between T. ehrhardti and T. cirrhosus is clear.
11
Trachops ehrhardti shows little haplotype sharing, and diversification only during the
Pleistocene. Trachops cirrhosus has high haplotypic diversity and FST values are expected
for panmitic populations, although comprising 6 geographically structured lineages. The
origin of the genus seems to have been in South America, given that T. c. coffini originated
2.96 million years ago, coinciding with the most recent estimate for the closure of the
Isthmus of Panama. The broadest ranged lineage of T. cirrhosus occupies several biomes of
South America, including the Atlantic Forest of northeastern Brazil. The current floristic
differences between the southern and northern Atlantic Forest and all biotic and abiotic
interactions involved may represent ecological barriers for the two species of Trachops.
Keywords: cryptic species, phylogeography, morphometrics, ecological niche modeling.
