Effect of Metabolites Produced by Trichoderma harzianum Biotypes and Agaricus bisporus on Their Respective Growth Radii in Culture

Trichoderma harzianum biotypes Th1, Th2, and Th3 produced volatile metabolites in vitro which had similar fungistatic effects on the growth of Agaricus bisporus. Metabolites present in agar colonized by these strains also inhibited mycelial growth of A. bisporus, although the reduction in growth was less in the presence of metabolites produced by biotype Th2 than that in the presence of metabolites produced by Th1 or Th3. A. bisporus produced metabolites in liquid culture that inhibited the growth of Th1 and Th3 but stimulated the growth of Th2. A compound(s) responsible for the inhibition and stimulation was extracted from A. bisporus culture filtrate and from compost-grown fruit bodies with n-butanol, but the identity of the compound(s) was not determined. We suggest that the stimulation of Th2 by metabolites produced by A. bisporus and the relatively low level of inhibition of A. bisporus by Th2 facilitate colonization of compost by both fungi. However, as compost colonization reaches a maximum, a change in the competitive balance in favor of Th2 results in the inhibition of fruit body production by A. bisporus and the devastating green mold epidemics affecting mushroom production.     

Uncoupling ecological innovation and speciation in sea snakes (Elapidae, Hydrophiinae, Hydrophiini)

The viviparous sea snakes (Hydrophiini) are by far the most successful living marine reptiles, with ～ 60 species that comprise a prominent component of shallow-water marine ecosystems throughout the Indo-West Pacific. Phylogenetically nested within the ～ 100 species of terrestrial Australo-Melanesian elapids (Hydrophiinae), molecular timescales suggest that the Hydrophiini are also very young, perhaps only ～ 8-13 Myr old. Here, we use likelihood-based analyses of combined phylogenetic and taxonomic data for Hydrophiinae to show that the initial invasion of marine habitats was not accompanied by elevated diversification rates. Rather, a dramatic three to six-fold increase in diversification rates occurred at least 3-5 Myr after this transition, in a single nested clade: the Hydrophis group accounts for ～ 80% of species richness in Hydrophiini and ～ 35% of species richness in (terrestrial and marine) Hydrophiinae. Furthermore, other co-distributed lineages of viviparous sea snakes (and marine Laticauda, Acrochordus and homalopsid snakes) are not especially species rich. Invasion of the oceans has not (by itself) accelerated diversification in Hydrophiini; novelties characterizing the Hydrophis group alone must have contributed to its evolutionary and ecological success.     

Recent rapid speciation and ecomorph divergence in Indo‐Australian sea snakes

The viviparous sea snakes (Hydrophiinae) are a young radiation of at least 62 species that display spectacular morphological diversity and high levels of local sympatry. To shed light on the mechanisms underlying sea snake diversification, we investigated recent speciation and eco‐morphological differentiation in a clade of four nominal species with overlapping ranges in Southeast Asia and Australia. Analyses of morphology and stomach contents identified the presence of two distinct ecomorphs: a ‘macrocephalic’ ecomorph that reaches >2 m in length, has a large head and feeds on crevice‐dwelling eels and gobies; and a ‘microcephalic’ ecomorph that rarely exceeds 1 m in length, has a small head and narrow fore‐body and hunts snake eels in burrows. Mitochondrial sequences show a lack of reciprocal monophyly between ecomorphs and among putative species. However, individual assignment based on newly developed microsatellites separated co‐distributed specimens into four significantly differentiated clusters corresponding to morphological species designations, indicating limited recent gene flow and progress towards speciation. A coalescent species tree (based on mitochondrial and nuclear sequences) and isolation‐migration model (mitochondrial and microsatellite markers) suggest between one and three transitions between ecomorphs within the last approximately 1.2 million to approximately 840 000 years. In particular, the macrocephalic ‘eastern’ population of Hydrophis cyanocinctus and microcephalic H. melanocephalus appear to have diverged very recently and rapidly, resulting in major phenotypic differences and restriction of gene flow in sympatry. These results highlight the viviparous sea snakes as a promising system for speciation studies in the marine environment.     

First molecular evidence for the phylogenetic placement of the enigmatic snake genus Brachyorrhos (Serpentes: Caenophidia)

BrachyorrhosSchlegel, 1826a is a terrestrial-fossorial snake genus endemic to eastern Indonesia that has been assigned to six different families and subfamilies within Colubroidea (advanced snakes) over the past ~200 years. Here we report the first molecular sequences for Brachyorrhos and use them to test the position of the genus within snake phylogeny. Our Bayesian and Maximum Likelihood analyses of three mitochondrial and one nuclear gene strongly resolve Brachyorrhos within the rear-fanged semiaquatic Homalopsidae (Colubroidea), as the sister taxon to all other genera and sampled species.     

The Knight and the King: two new species of giant bent-toed gecko (Cyrtodactylus,Gekkonidae, Squamata) from northern New Guinea,with comments on endemism in the North Papuan Mountains

The diverse biota of New Guinea includes many nominally widespread species that actually comprise multiple deeply divergent lineages with more localised histories of evolution. Here we investigate the systematics of the very large geckos of the Cyrtodactylusnovaeguineae complex using molecular and morphological data. These data reveal two widespread and divergent lineages that can be distinguished from each other, and from type material of Cyrtodactylusnovaeguineae, by aspects of size, build, coloration and male scalation. On the basis of these differences we describe two new species. Both have wide distributions that overlap extensively in the foothill forests of the North Papuan Mountains, however one is seemingly restricted to hill and lower montane forests on the ranges themselves, while the other is more widespread throughout the surrounding lowlands. The taxon endemic to the North Papuan Mountains is related to an apparently lowland form currently known only from Waigeo and Batanta Island far to the west – hinting at a history on island arcs that accreted to form the North Papuan Mountains.     

Harvest Effects on Blood Pythons in North Sumatra

Wildlife populations exposed to intense harvesting often exhibit shifts in attributes of the commercial offtake (e.g., numbers, body sizes, body condition, sex ratios, size at maturation, reproductive frequency). To look for such changes, we examined >2,500 specimens of field-collected blood pythons (Python brongersmai) brought to 2 processing facilities in North Sumatra over 2 survey periods (1996–1997 and 2014–2015). Over the 18 years between our surveys, approximately 900,000 blood pythons were taken from Indonesia for the commercial trade; North Sumatra accounted for about 35% of that trade volume. Between survey periods, numbers of snakes brought to 1 processing facility decreased and mean body size increased, whereas at the second facility numbers and sizes of snakes remained the same. Overall, the pythons collected in 2015–2016 were thinner-bodied than in 1996–1997, with fewer immature animals and a reduced size at maturation and reproductive frequency among females. Clutch size relative to maternal size decreased also. These temporal shifts in python demographics likely reflect a response to harvesting, although ecosystem changes may have played a role. Compared to other squamate reptiles, blood pythons may be more vulnerable to over-harvesting because most snakes are intensively collected from discrete habitat patches (oil palm plantations), and the species can be targeted by specific hunting methods. To ensure sustainability of the harvest, we recommend minimum and maximum size limits for skins used in the commercial trade, and more intensive monitoring at processing facilities. © 2019 The Wildlife Society.     

Multilocus phylogeography of the sea snake Hydrophis curtus reveals historical vicariance and cryptic lineage diversity

The Indo‐Australian archipelago (IAA) supports the world's highest diversity of marine fish, invertebrates and reptiles. Many of the marine fish and invertebrates show congruent phylogeographic patterns, supporting a view that the region's complex geo‐climatic history has played an important role in generating its exceptional biodiversity. Here, we examine population genetic structure of the viviparous sea snake, Hydrophis curtus, to assess how past and present barriers to gene flow in the IAA have contributed to genetic and species diversity in a fully marine reptile. Mitochondrial and anonymous nuclear sequences and ten microsatellite loci were used to identify patterns of historical genetic structure and population expansion, reconstruct dated genealogies and assess levels of recent gene flow. These markers revealed strong concordant geographic structure within H. curtus with a prominent genetic break between populations broadly distributed in the Indian Ocean and the West Pacific. These populations were estimated to have diverged in the late Pliocene or early Pleistocene, and microsatellite admixture analyses suggested limited recent gene flow between them despite the current lack of barriers to dispersal, indicating possible cryptic species. Subsequent divergence in the mid–late Pleistocene was detected within the West Pacific clade among the populations in the Phuket‐Thailand region, South‐East Asia and Australia, and two of these populations also showed genetic signals of recent range expansions. Our results show that climatic fluctuations during the Plio‐Pleistocene generated high levels of cryptic genetic diversity in H. curtus, and add to similar findings for diverse other marine groups in the IAA.     

Ecological divergence among sympatric colour morphs in blood pythons, Python brongersmai

Blood pythons in northeastern Sumatra display a series of discrete colour morphs, even among hatchlings within a single clutch. The first step towards understanding the maintenance of this polymorphism is to test the null hypothesis that colour variation in this species has no major biological correlates. Data on >2,000 blood pythons killed for the commercial leather industry enabled us to test, and reject, this hypothesis. The four colour morphs differed significantly in most of the traits that we measured, including temporal and spatial abundances, sex ratios, age structures, mean adult body sizes, body shapes (tail length and body mass relative to snout-vent length), energy stores, numbers of gut parasites, prey types, feeding frequencies and clutch sizes. The causal basis for these associations remains unclear, but is likely to involve three processes: direct effects of colour, linkages between genes for colour and other traits, and correlated spatial heterogeneity in colour, morphology and ecology. The colour polymorphism may be maintained by frequency-dependent selection and genotype-specific habitat selection, because these sedentary ambush predators are under strong selection for effective camouflage to hide them from both predators and potential prey. In support of this hypothesis, similar colour polymorphisms have evolved independently in several other snake taxa that rely upon ambush predation. Received: 18 December 1997 / Accepted: 23 March 1998