Climatic niche conservatism in a clade of disease vectors (Diptera: Phlebotominae)

Sandflies of the family Psychodidae show notable diversity in both disease vector status and climatic niche. Some species (in the subfamily Phlebotominae) transmit Leishmania parasites, responsible for the disease leishmaniasis. Other Psychodidae species do not. Psychodid species ranges can be solely tropical, confined to the temperate zones, or span both. Studying the relationship between the evolution of disease vector status and that of climatic niche affords an understanding not only of the climate conditions associated with the presence and species richness of Leishmania vectors, but also allows the study of the extent to which the climatic niches of psychodid flies are conserved, in a context with implications for global human health. We obtained observation site data, and associated climate data, for 223 psychodid species to understand which aspects of climate most closely predict distribution. Temperature and seasonality are strong determinants of species occurrence within the clade. We built a mitochondrial DNA phylogeny of Psychodidae, and found a positive relationship between pairwise genetic distance and climate niche differentiation, which indicates strong niche conservatism. This result is also supported by strong phylogenetic signals of metrics of climate differentiation. Finally, we used ancestral trait reconstruction to infer the tropicality (i.e., proportion of latitudinal range in the tropics minus the proportion of the latitudinal range in temperate areas) of ancestral species, and counted transitions to and from tropicality states, finding that tropical and temperate species respectively produced almost entirely tropical and temperate descendant species, a result consistent for vector and non-vector species. Taken together, these results imply that while vectors of Leishmania can survive in a variety of climates, their climate niches are strongly predicted by phylogeny.

Recreational fishers’ perceptions of climate change

Shifts in marine species distributions associated with climate change occur across large spatial areas and long time periods. Marine recreational fishing occurs in most countries with many participants interacting regularly with the environment, yet there have been few studies on the views of recreational fishers towards climate change. This study aims to assess perceptions of climate change for a boat-based recreational fishery in Western Australia, where fishing occurs across a wide latitudinal range, from tropical to temperate waters. Perceptions of climate change were assessed by fisher demographics and fishing behaviour. One in two respondents noticed changes in species types and distributions, with metropolitan residents and avid fishers more likely to notice these changes. Two out of three respondents considered climate change is occurring, recognition of which was higher amongst metropolitan residents, females, and younger respondents. Males and older respondents, on the other hand considered themselves to have more knowledge of climate change science. This study provides a baseline to assist in informing policy changes that might be required to address the impacts of climate change. Studies of this kind can also build support for citizen science programs to enhance data collection across the spatial and temporal time scales required to observe climate change.

Evolutionary drivers of the hump-shaped latitudinal gradient of benthic polychaete species richness along the Southeastern Pacific coast

Latitudinal diversity gradients (LDG) and their explanatory factors are among the most challenging topics in macroecology and biogeography. Despite of its apparent generality, a growing body of evidence shows that ‘anomalous’ LDG (i.e., inverse or hump-shaped trends) are common among marine organisms along the Southeastern Pacific (SEP) coast. Here, we evaluate the shape of the LDG of marine benthic polychaetes and its underlying causes using a dataset of 643 species inhabiting the continental shelf (<200 m depth), using latitudinal bands with a spatial resolution of 0.5°, along the SEP (3–56° S). The explanatory value of six oceanographic (Sea Surface Temperature (SST), SST range, salinity, salinity range, primary productivity and shelf area), and one macroecological proxy (median latitudinal range of species) were assessed using a random forest model. The taxonomic structure was used to estimate the degree of niche conservatism of predictor variables and to estimate latitudinal trends in phylogenetic diversity, based on three indices (phylogenetic richness (PDSES), mean pairwise distance (MPDSES), and variation of pairwise distances (VPD)). The LDG exhibits a hump-shaped trend, with a maximum peak of species richness at ca. 42° S, declining towards northern and southern areas of SEP. The latitudinal pattern was also evident in local samples controlled by sampling effort. The random forest model had a high accuracy (pseudo-r2 = 0.95) and showed that the LDG could be explained by four variables (median latitudinal range, SST, salinity, and SST range), yet the functional relationship between species richness and these predictors was variable. A significant degree of phylogenetic conservatism was detected for the median latitudinal range and SST. PDSES increased toward the southern region, whereas VPD showed the opposite trend, both statistically significant. MPDSES has the same trend as PDSES, but it is not significant. Our results reinforce the idea that the south Chile fjord area, particularly the Chiloé region, was likely the evolutionary source of new species of marine polychaetes along SEP, creating a hotspot of diversity. Therefore, in the same way as the canonical LDG shows a decline in diversity while moving away from the tropics; on this case the decline occurs while moving away from Chiloé Island. These results, coupled with a strong phylogenetic signal of the main predictor variables suggest that processes operating mainly at evolutionary timescales govern the LDG.

100Identification of a latitude gradient in the prevalence of Primary Biliary Cholangitis in Australia

Background Primary biliary cholangitis (PBC) is an autoimmune destructive condition of the gall bladder, with environmental factors like sun exposure implicated in its aetiology, similar to multiple sclerosis. PBC prevalence varies significantly and appears to have a positive latitudinal gradient. To determine whether there was a latitudinal gradient of PBC prevalence in Australia using two methods of prevalence estimation: private pathology anti-mitochondrial antibody (AMA) results, the primary diagnostic test for PBC, and ursodeoxycholic acid (UDCA) prescriptions, the sole pharmacological treatment for PBC. Methods We investigated the latitudinal variation in PBC prevalence across the states and territories of Australia (latitudinal range 18.0° to 42.7°S) using pathology-based (private pathology AMA results search (three of the major private pathology companies in Australia which cover 77% of all private pathology testing) and PBC-specific prescription databases (prescriptions for UDCA). Results Pathology-based PBC prevalence was significantly increased with latitude, such that the postcodes in the highest quintile of latitude (encompassing the south coastal areas of the Australian mainland and insular Tasmania (latitude range -37.75 to -42.72)) had 1.83-times higher frequencies than those in the lowest quintile (encompassing tropical and southern Queensland (latitude range -18.02 to -27.59). Analogous results were seen for state-based UDCA prescriptions, being 2.31-times higher in Tasmania than Queensland. Conclusions We have found for the first time that the prevalence of PBC significantly varies with latitude in Australia. While the most immediate mediating factors underlying this association would be ultraviolet radiation and vitamin D levels, studies to substantiate this mechanism are needed. Key messages In line with some other autoimmune conditions, PBC shows a significant positive latitudinal gradient, with nearly 2-times higher prevalence in the southernmost state than the northernmost.

Begonia of Vietnam: an updated checklist, including a new species and a new record

Vietnam is an important hotspot for Begonia in Southeast Asia. Due to its broad latitudinal range and varied terrain, it has developed a rich biodiversity of flora, of which the genus of Begonia is one of the most striking taxa. In this study, we provide a checklist of Begonia found in Vietnam, including a new species: B. jubar V.T.Pham & C.W.Lin, which is described and illustrated. In addition, Begonia modestiflora Kurz is recorded for the first time in Vietnam.

CATION EXCHANGE CAPACITY OF THE HUMUS PART OF THE WEST SIBERIAN TRANSECT SOILS

The article analyzes the change in the indicator of the cation exchange capacity (CEC) in the humus of the latitudinal series of soils in Western Siberia. It is shown that not all humus substances are able to perform the function of cation exchange and participate in the formation of the organic part of the soil EC. It is shown that the organic matter in the latitudinal range of soils in Western Siberia is distributed in accordance with the known geographical pattern of the distribution of the total humus stock and the main characteristics of this stock. An unconventional evaluation method for determining the EC is proposed using analytical data on the content of acidic functional groups in humic acids and the composition of humic substances, which allows us to separately assess the contribution of humic and fulvic acids in the composition of the EC of the soil.

Consuming Costly Prey: Optimal Foraging and the Role of Compensatory Growth

Some prey are exceptionally difficult to digest, and yet even non-specialized animals may consume them—why? Durophagy, the consumption of hard-shelled prey, is thought to require special adaptations for crushing or digesting the hard shells to avoid the many potential costs of this prey type. But many animals lacking specializations nevertheless include hard-bodied prey in their diets. We describe several non-mutually exclusive adaptive mechanisms that could explain such a pattern, and point to optimal foraging and compensatory growth as potentially having widespread importance in explaining costly-prey consumption. We first conducted a literature survey to quantify the regularity with which non-specialized teleost fishes consume hard-shelled prey: stomach-content data from 325 teleost fish species spanning 82 families (57,233 stomach samples) demonstrated that non-specialized species comprise ~75% of the total species exhibiting durophagy, commonly consuming hard-shelled prey at low to moderate levels (~10–40% as much as specialists). We then performed a diet survey to assess the frequency of molluscivory across the native latitudinal range of a small livebearing fish, Gambusia holbrooki, lacking durophagy specializations. Molluscivory was regionally widespread, spanning their entire native latitudinal range (&gt;14° latitude). Third, we tested for a higher frequency of molluscivory under conditions of higher intraspecific resource competition in Bahamian mosquitofish (Gambusia spp.). Examining over 5,300 individuals, we found that molluscivory was more common in populations with higher population density, suggesting that food limitation is important in eliciting molluscivory. Finally, we experimentally tested in G. holbrooki whether molluscivory reduces growth rate and whether compensatory growth follows a period of molluscivory. We found that consumption of hard-shelled gastropods results in significantly reduced growth rate, but compensatory growth following prior snail consumption can quickly mitigate growth costs. Our results suggest that the widespread phenomenon of costly-prey consumption may be partially explained by its relative benefits when few alternative prey options exist, combined with compensatory growth that alleviates temporary costs.