Evolution and Biogeographic History of Rubyspot Damselflies (Hetaerininae: Calopterygidae: Odonata)

Abstract

The damselflies Hetaerininae, a subfamily of Calopterygidae, comprise four genera distributed from North to South America: Hetaerina, Mnesarete, Ormenophlebia and Bryoplathanon. While several studies have focused on the intriguing behavioral and morphological modifications within Hetaerina, little of the evolutionary history of the group is well understood. Understanding the biogeographical history of Hetaerininae is further complicated by uncertainty in important geological events, such as the closure of the Central American Seaway (CAS). We generated a phylogenetic hypothesis to test the relationships and divergence times within Hetaerininae using IQtree and BEAST2 and found that Mnesarete and Ormenophlebia render Hetaerina paraphyletic. Reclassification of the genera within Hetaerininae is necessary based on our results. We also tested the fit to our dataset of two different hypotheses for the closure of CAS. Our results supported a gradual closure, starting in the Oligocene and ending in the Pliocene. Using Ancestral Character State Reconstruction, we found that the rubyspot, which is associated with higher fecundity in several species, was ancestral for Hetaerininae and subsequently lost four times. Estimates of diversification in association with the rubyspot are needed to understand the plasticity of this important character. Forest habitat was the ancestral state for Hetaerininae, with transitions to generalist species of Hetaerina found primarily in the Mesoamerican region. These results add to our understanding of the relationship between morphology, biogeography and habitat in a charismatic group of damselflies.

Niche differentiation, reproductive interference, and range expansion

“…The dashed lines have a slope of 1, and thus points above (below) the lines are cases in which H. titia had a larger (smaller) value than the other species. with estimated species divergence times of 10-36 million years (Standring et al, 2022). Our finding that sympatric species have more similar climatic niches than allopatric species is not surprising from a statistical standpoint, because the same result would be expected if species ranges overlapped randomly (Warren et al, 2014).…”

“…To account for phylogenetic nonindependence in comparisons of niche metrics between species pairs (Drury et al, 2018;Tobias et al, 2014), we fit phylogenetic linear mixed models (PLMMs) with the Markov chain Monte Carlo (MCMC) algorithm in 'MCMCglmm' 2.3 (Hadfield, 2010). We used the fossil-calibrated phylogeny of Standring et al (2022), appending C. diminiata (Burmeister) and C. amata (Hagen) based on the topology of Waller and Svensson (2017) (Figure S2). C. angustipennis (Selys) could not be included because no phylogenetic data were available for this species.…”

“…americana spp.'. The melanic wing pigmentation that makes H. titia distinct from congeners increases its resemblance to Calopteryx (Figure 3;Córdoba-Aguilar et al, 2007), a younger genus in the same family (Calopterygidae; Standring et al, 2022). Our niche comparisons include 12 of the 13 species of Hetaerina and all five species of Calopteryx that occur in North America.…”

“…Release from reproductive interference could explain why H. titia has the largest latitudinal range and occurs in sympatry with the most congeners (Figure 2). The species with the largest longitudinal range, H. americana (Fabricius), was recently split into two sister species based on genetic data (Standring et al, 2022;Vega-Sánchez et al, 2019, 2020, but the occurrence records are indistinguishable; we refer to this monophyletic subclade as 'H. americana spp.'.…”

A chromosome-level genome assembly for the smoky rubyspot damselfly (Hetaerina titia)

“…Recently, a genome assembly of Hetaerina americana was published ( Grether et al 2023 ), enabling genomic research on this group of charismatic insects. However, because the best estimate for the crown age for the Hetaerina is 36.2 million years ago (Mya) and phylogenetic analyses demonstrate that the clade is paraphyletic and requires taxonomic revision ( Standring et al 2022 ), more genomic resources beyond H. americana are needed to fully resolve species relationships and support genomic research on this taxon. Moreover, although the H. americana assembly provides a high-quality set of genomic resources, the scaffolds are not fully resolved into chromosomes; estimates from Calopteryx spp.…”