Matthew H. Van Dam

Phylogenetic niche conservatism explains an inverse latitudinal diversity gradient in freshwater arthropods

The underlying mechanisms responsible for the general increase in species richness from temperate regions to the tropics remain equivocal. Many hypotheses have been proposed to explain this astonishing pattern but additional empirical studies are needed to shed light on the drivers at work. Here we reconstruct the evolutionary history of the cosmopolitan diving beetle subfamily Colymbetinae, the majority of which are found in the Northern hemisphere, hence exhibiting an inversed latitudinal diversity gradient. We reconstructed a dated phylogeny using 12 genes, to investigate the biogeographical history and diversification dynamics in the Colymbetinae. We aimed to identify the role that phylogenetic niche conservatism plays in the inversed diversification pattern seen in this group. Our results suggest that Colymbetinae originated in temperate climates, which supports the hypothesis that their distribution is the result of an ancestral adaptation to temperate environmental conditions rather than tropical origins, and that temperate niche conservatism can generate and/or maintain inverse latitudinal diversity gradients.

Impact of Off-Road Vehicle Use on Dune Endemic Coleoptera

Scarab diversity in the Algodones Dunes (Imperial Co., CA) was assessed using a series of light-bucket transects to ascertain the impact of off-road vehicle (ORV) use. We compared dune endemic scarab species on the dunes south of Hwy. 78 that receive intense ORV use and the populations on the protected dunes north of Hwy. 78. We also compared the total numbers of Coleoptera collected. Our data indicate that unprotected dunes experienced a signiÞcant decline in Coleoptera populations, diversity, and species evenness. These results demonstrate that ORV use has a severe negative impact on Coleoptera that inhabit sand dunes.Scarab diversity in the Algodones Dunes (Imperial Co., CA) was assessed using a series of light-bucket transects to ascertain the impact of off-road vehicle (ORV) use. We compared dune endemic scarab species on the dunes south of Hwy. 78 that receive intense ORV use and the populations on the protected dunes north of Hwy. 78. We also compared the total numbers of Coleoptera collected. Our data indicate that unprotected dunes experienced a significant decline in Coleoptera populations, diversity, and species evenness. These results demonstrate that ORV use has a severe negative impact on Coleoptera that inhabit sand dunes.

Macroevolution of hyperdiverse flightless beetles reflects the complex geological history of the Sunda Arc

The Sunda Arc forms an almost continuous chain of islands and thus a potential dispersal corridor between mainland Southeast Asia and Melanesia. However, the Sunda Islands have rather different geological histories, which might have had an important impact on actual dispersal routes and community assembly. Here, we reveal the biogeographical history of hyperdiverse and flightless Trigonopterus weevils. Different approaches to ancestral area reconstruction suggest a complex east to west range expansion. Out of New Guinea, Trigonopterus repeatedly reached the Moluccas and Sulawesi transgressing Lydekker′s Line. Sulawesi repeatedly acted as colonization hub for different segments of the Sunda Arc. West Java, East Java and Bali are recognized as distinct biogeographic areas. The timing and diversification of species largely coincides with the geological chronology of island emergence. Colonization was not inhibited by traditional biogeographical boundaries such as Wallace’s Line. Rather, colonization patterns support distance dependent dispersal and island age limiting dispersal.

Ultraconserved elements (UCEs) resolve the phylogeny of Australasian smurf-weevils

Weevils (Curculionoidea) comprise one of the most diverse groups of organisms on earth. There is hardly a vascular plant or plant part without its own species of weevil feeding on it and weevil species diversity is greater than the number of fishes, birds, reptiles, amphibians and mammals combined. Here, we employ ultraconserved elements (UCEs) designed for beetles and a novel partitioning strategy of loci to help resolve phylogenetic relationships within the radiation of Australasian smurf-weevils (Eupholini). Despite being emblematic of the New Guinea fauna, no previous phylogenetic studies have been conducted on the Eupholini. In addition to a comprehensive collection of fresh specimens, we supplement our taxon sampling with museum specimens, and this study is the first target enrichment phylogenomic dataset incorporating beetle specimens from museum collections. We use both concatenated and species tree analyses to examine the relationships and taxonomy of this group. For species tree analyses we present a novel partitioning strategy to better model the molecular evolutionary process in UCEs. We found that the current taxonomy is problematic, largely grouping species on the basis of similar color patterns. Finally, our results show that most loci required multiple partitions for nucleotide rate substitution, suggesting that single partitions may not be the optimal partitioning strategy to accommodate rate heterogeneity for UCE loci.

Phylogeography and population genomics of a lotic water beetle across a complex tropical landscape

The habitat template concept applied to a freshwater system indicates that lotic species, or those which occupy permanent habitats along stream courses, are less dispersive than lentic species, or those that occur in more ephemeral aquatic habitats. Thus, populations of lotic species will be more structured than those of lentic species. Stream courses include both flowing water and small, stagnant microhabitats that can provide refuge when streams are low. Many species occur in these microhabitats but remain poorly studied. Here, we present population genetic data for one such species, the tropical diving beetle Exocelina manokwariensis (Dytiscidae), sampled from six localities along a ~300 km transect across the Birds Head Peninsula of New Guinea. Molecular data from both mitochondrial (CO1 sequences) and nuclear (ddRAD loci) regions document fine‐scale population structure across populations that are ~45 km apart. Our results are concordant with previous phylogenetic and macroecological studies that applied the habitat template concept to aquatic systems. This study also illustrates that these diverse but mostly overlooked microhabitats are promising study systems in freshwater ecology and evolutionary biology. With the advent of next‐generation sequencing, fine‐scale population genomic studies are feasible for small nonmodel organisms to help illuminate the effect of habitat stability on species’ natural history, population structure and geographic distribution.

Stream flow alone does not predict population structure of diving beetles across complex tropical landscapes

Recent theoretical advances have hypothesized a central role of habitat persistence on population genetic structure and resulting biodiversity patterns of freshwater organisms. Here, we address the hypothesis that lotic species, or lineages adapted to comparably geologically stable running water habitats (streams and their marginal habitats), have high levels of endemicity and phylogeographic structure due to the persistent nature of their habitat. We use a nextRAD DNA sequencing approach to investigate the population structure and phylogeography of a putatively widespread New Guinean species of diving beetle, Philaccolilus ameliae (Dytiscidae). We find that P. ameliae is a complex of morphologically cryptic, but geographically and genetically well‐differentiated clades. The pattern of population connectivity is consistent with theoretical predictions associated with stable lotic habitats. However, in two clades, we find a more complex pattern of low population differentiation, revealing dispersal across rugged mountains and watersheds of New Guinea up to 430 km apart. These results, while surprising, were also consistent with the original formulation of the habitat template concept by Southwood, involving lineage‐idiosyncratic evolution in response to abiotic factors. In our system, low population differentiation might reflect a young species in a phase of range expansion utilizing vast available habitat. We suggest that predictions of life history variation resulting from the dichotomy between lotic and lentic organisms require more attention to habitat characterization and microhabitat choice. Our results also underpin the necessity to study fine‐scale processes but at a larger geographical scale, as compared to solely documenting macroecological patterns, to understand ecological drivers of regional biodiversity. Comprehensive sampling especially of tropical lineages in complex and threatened environments such as New Guinea remains a critical challenge.

Four new species of Trigonopterus Fauvel from the island of New Britain (Coleoptera, Curculionidae)

Abstract The hyperdiverse genus Trigonopterus has its center of diversity in Melanesia, but only a single species is recorded from the Bismarck Archipelago to date. Here we describe four new species from the island of New Britain: Trigonopterus chewbacca sp. n., Trigonopterus obsidianus sp. n., Trigonopterus puncticollis sp. n. and Trigonopterus silaliensis sp. n. We provide cytochrome oxidase subunit I (cox1) sequences of the new species and a key to all five species known from the Bismarck Archipelago.

Correction: Ultraconserved elements (UCEs) resolve the phylogeny of Australasian smurf-weevils

[This corrects the article DOI: 10.1371/journal.pone.0188044.].

Description of the Third-instar Larva and Adult Male of Megasoma sleeperi Hardy (Scarabaeidae: Dynastinae)

Abstract The third-instar larvae of Megasoma sleeperi Hardy are illustrated and described based upon three larval specimens. The larvae were hatched in captivity from eggs obtained from adult females collected near Glamis, Imperial Co., California, USA, in mid-September 2003. Their structure is compared with that of Megasoma occidentalis Bolivar y Pieltain et al. and Megasoma cedrosa Hardy in order to find species-level characters. A description of the adult male is included, based upon the examination of three males.

Description of the Larva of Pseudocotalpa sonorica Hardy (Scarabaeidae: Rutelinae: Rutelini) with Notes on Life History

Abstract Larvae of the genus Pseudocotalpa Hardy, 1971 are described for the first time based on the larva of P. sonorica Hardy 1974. Characters used to separate Pseudocotalpa from similar genera are given. Life history observations of adults of P. sonorica are also given.Larvae of the genus Pseudocotalpa Hardy, 1971 are described for the first time based on the larva of P. sonorica Hardy 1974. Characters used to separate Pseudocotalpa from similar genera are given. Life history observations of adults of P. sonorica are also given. The genus Pseudocotalpa described by Hardy, 1971, now consists of three species: Pseudocotalpa andrewsi Hardy, 1971; Pseudocotalpa giulianii Hardy, 1974; and Pseudocotalpa sonorica Hardy, 1974. This genus is strongly associated with sand dunes of the southwest deserts. The only previous mention of Pseudocotalpa larva in the literature was that of Rust (1985) on P. giulianii. Rust also gives detailed description of life history habits. The life history of P. andrewsi was discussed by Hardy and Andrews (1986). Ritcher (1966) described the larvae of genera closely related to Pseudocotalpa. Material and Methods Adults of Pseudocotalpa sonorica were collected north of the Osborne Overlook in the Algodones Sand Dunes, Imperial Co., California, USA (32859.2639N 115808.1019W) on 22 March 2002. An adult female was placed in a coffee can filled with moist sand from the dunes and subsequently deposited about 25 eggs. The resulting larvae were raised to the third instar on oak leaf mulch. The following description is based on two of these larvae. Specimens of adults and larvae are deposited to the Los Angeles County Museum of Natural History and Entomological Research Museum University of California Riverside. Description. Head. Cranium (Fig. 11) Greatest width of head capsule 6.8 mm. Epicranium light reddish-brown; surface smooth with setose punctures. Frontal suture absent. Epicranial suture only present at occiput. Setae spinelike or thin hairlike (Fig. 11), becoming longer laterally. Two distinct pits on side of cranium. Genal margins marked with fine setae. Ocellus absent. Clypeus: Form subtrapezoidal. Preclypeus smooth pale, tan, with row of minute setae bordering top; postclypeus same color as cranium. Labrum: Form subovate, right side with indentation on edge. Surface convex, except distal third flattened, setigenous punctate. Only distinct setae on surface are fine, hairlike setae, all in deep pits; two on upper half near center; one seta on each side of 31 The Coleopterists Bulletin, 60(01):31–36. 2006.