A rapid survey of herpetofaunal diversity in Nijhum Dwip National Park, Bangladesh

The ecological effects of habitat use by herpetofaunal species vary widely and recognizing relative habitat value will help to improve conservation theory and practice in a particular landscape. To understand how different habitat uses influence diversity in riparian landscapes, we studied reptile and amphibian assemblages across major habitats (agricultural land, forest, human habitation, and waterbodies) in Nijhum Dwip National Park, Bangladesh. A total of 35 herpetofaunal species were found; among them, 17 were directly observed and 18 were reported from a questionnaire survey. Among the observed species, the Asian Common Toad Duttaphrynus melanostictus was the most commonly seen (relative abundance 0.32). We found that forest habitat contained a greater diversity of herpetofauna than other habitats followed by agricultural land, human habitation, and waterbodies. We also found 8 habitat specialist species and 9 generalist species in this study. Our results show that different habitats support different species assemblages in Nijhum Dwip National Park, signifying the importance of diversified habitats for the herpetofaunal population. Understanding this importance is crucial for identifying matrix environments that can complement the forest habitats of sensitive as well as specialist herpetofaunal species.

Effects of Open and Forest Habitats on Distribution and Diversity of Bumblebees (Bombus) in the Małopolska Upland (Southern Poland): Case Study

Bumblebees are an important insect group occurring in different land ecosystems, but the number of these species has declined dramatically across Poland as well as in Europe in recent years. The fragmentation of bumblebee habitats influences the abundance and richness in community composition and trophic and competitive interactions. During the years 2003–2006 and 2017–2020, we studied the diversity and distribution of bumblebee species in two natural (boron-mixed Vaccinio-Piceetea and riparian forest Querco-Fagetea) and two semi-natural (segetal-ruderal Stellarietea mediae ruderal Artemisietea vulgaris) habitats in southern Poland. For that, we evaluated how habitats as well as local flowering communities influenced bumblebees’ abundance, richness, and community composition in 16 sites (which are located in four parks). Bumblebee communities responded to environmental factors in different ways according to the type of habitat. Vegetation factors were the most important drivers of bumblebee community structures. Forests showed the lowest bumblebee abundance, richness, and diversity, and the highest dominance levels of these parameters were found in the open ruderal-segetal habitats. The meadows from the Molinio arrhenatheretea class were characterized by bumblebee communities with a more complex structure. Species diversity was positively correlated with open ruderal-segetal habitats, and negatively with mixed forest cover, while abundance was positively correlated with forest cover. Studies like this are necessary to anticipate the impact of habitat fragmentation on bumblebee decline.

Patterns of Bat Diversity in an Undisturbed Forest and Forest Mosaic Habitats of the Afromontane Forest Biome of Western Cameroon

Anthropogenic activities continue to degrade natural montane ecosystems globally. Bats communities are altered by these changes. We analyzed how bats are affected by human-induced habitat changes by comparing the bat species diversity and functional diversity in undisturbed forest habitats and disturbed forest habitats of the Afromontane biome of Cameroon. We recorded 244 individuals from 13 species in the undisturbed forest, while 233 individuals from 16 species were recorded in the disturbed forest. Bat diversity was higher in disturbed habitats (D = 0.84) than undisturbed habitats (D = 0.67). Jackknife 1 species richness estimator suggests 21.53 species for the disturbed forest and 19.30 in the undisturbed forest. Closed-space forager insectivorous bats made up nearly half of the species in the undisturbed forest, but this dropped to 25% in the disturbed forest, meanwhile, edge-space foragers increased in the disturbed forest. Bat community analyses by ordination revealed a distinct bat community composition between the two forest types, demonstrated as a significant difference in diversity between the two forest types. The distribution of Rousettus aegyptiacus, Myonycteris angolensis, Hipposideros cf. ruber, and Micropteropus pusillus contribute the most to the difference in bat community composition between the two forest types. Edge and open-space species were likely to benefit from additional resources provided by the disturbed area, by expanding their range and distribution. However, this may not compensate for the decline in the population of forest species caused by the loss of pristine forests, thus measures to conserve montane forest remnants should be of utmost significance.

First Report of Entomopathogenic Fungi Occurrence in Forest Soils in Croatia

Entomopathogenic fungi (EPF) in Croatian forests are known only from observations of insect cadavers that show obvious signs of disease. To date, their presence in soils has not been investigated. The aim of this study was to investigate their occurrence, diversity, and distribution, and to assess their density in tested soils. Soil samples were collected during 2018, 2019, and 2020 at different localities throughout the country, and analyzed by using a method of isolation of fungi on selective culture media. To assess the density of EPF in tested soils, colonies of individual fungal species were counted and recorded; the results were expressed as the number of colony-forming units (CFU) per gram of dry soil. After morphological and molecular analysis, five entomopathogenic fungal genera were identified: Beauveria spp., Metarhizium spp., Purpureocillium spp., Lecanicillium spp., and Paecilomyces spp. Results also showed that the range of a total EPF colony density in the soil varies from 4 × 103 to 27.4 × 103 CFU g−1. The most common were EPF of the genus Beauveria, which were recorded at four of five locations, and at 16 of 25 sampling points, but the highest average number (density) of colonies belonged to the genus Metarhizium. Since this type of research was never conducted in Croatia previously, this is the first evidence that insect pathogenic fungi are present in soils of different natural forest habitats. Such research can be useful in selecting and utilizing entomopathogens that are suitable for biological pest control in certain target areas.

Diversity of terrestrial gastropods in Kabylia region (Tizi-Ouzou, Northern Algeria)

The goal of this study was to record the malacofauna of the Kabylia region, Tizi-Ouzou, in Northern Algeria, at the edge of the Mediterranean Sea, and to report the distribution pattern of terrestrial gastropod diversity in five different types of habitat (dune, agricultural fields, rural sites, forests, and mountain locations). A total of 33 species of terrestrial snails and slugs were recorded, which represented 27 genera of 19 families, mainly Geomitridae and Helicidae. The rural habitat was the richest, with 23 species, while the mountain habitat yielded 20 species. The dune and forest habitats showed the smallest species richness.

Disentangling factors that assemble New Zealand's ant communities

<p>Several biotic and abiotic stressors can influence community assembly. The negative co-occurrence patterns observed within many communities, for example, may derive either from behavioural similarities (e.g. species displaying high aggression levels towards each other) or habitat preference. I evaluated the role of several stressors that may shape New Zealand’s ant communities. First, I investigated (in chapter 2) the co-occurrence patterns of two native ant communities located within transitional grassland-forest habitats. I also monitored the temperature variation in these habitats over a one-year period. I found that grasslands are exposed to higher temperature variation than forest habitats. I also found that some ants are mostly associated with forest habitats and others with grasslands. Using null models to examine these communities, I found evidence that two ant species (Monomorium antarcticum and Prolasius advenus) exhibit negative co-occurrence patterns. In the reminder of my thesis I developed a series of laboratory-based experiments to examine the processes that could explain the co-occurrence patterns that I observed in these ant communities. In chapter 3, I subjected heterospecific groups of ants to interactions in controlled conditions. I asked if interspecific aggression predict the survival probability and co-occurrence patterns described in chapter 2. My results demonstrated that aggression predicted the survival probability of interacting ant species and their co-occurrence patterns. I argued that aggressive behaviour might reflect the risks imposed by competitors. Differences in aggression may thus be a key factor influencing sympatric and allopatric co-occurrence patterns of these ant communities. In chapter 4, I tested the hypotheses that arrival sequence and diet influence the strength of interactions between colonies of two species that exhibited negative co-occurrence patterns (P. advenus and M. antarcticum). When arriving first, P. advenus displayed increased aggression and M. antarcticum a defensive reaction. The adoption of a defensive reaction by M. antarcticum increased their colony survival probability. Changes in carbohydrate and protein availability modulated colony activity rates of both species. These results indicate that arrival sequence can modulate the territorial behaviour displayed by interacting species in situations of conflict. Also, I showed that these ant species adjust their foraging activity rates in according to their diet, but different species do so differently. In chapter 5, I expanded the scope of chapter 4 and asked if aggression and foraging behaviour of P. advenus and M. antarcticum change in different conditions of temperature, diet and group size. For both ant species, changes in temperature had stronger effects on small than large colonies. Small groups of M. antarcticum displayed higher foraging activity at lower temperatures. Conversely, small groups of P. advenus displayed higher foraging activity at high temperatures. Also, small M. antarcticum colonies displayed increased aggression and significantly reduced the size of large P. advenus colonies, regardless of temperature and diet. These results suggest that P. advenus and M. antarcticum perform differently at different temperatures. Furthermore, I demonstrated that the persistence of these small colonies might be related to their ability to modulate foraging activities and interspecific aggression according to the environment. I also investigated (in chapter 6) the effects of a neurotoxic pesticide (neonicotinoid) on a native (M. antarcticum) and an invasive ant (Linepithema humile). I tested whether sublethal contamination with a neonicotinoid affects foraging, fitness and the outcome of interspecific interactions between these ants. Overall, pesticide exposure increased aggression of the invasive ant and reduced the aggression of the native species. Importantly, non-exposed individuals of the invasive species subjected to interactions against exposed natives were less aggressive, but more likely to survive. These results suggest that the modification of the physicochemical environment by pesticide contamination could change the dynamics of communities and influence invasion success. Overall, this thesis highlights that synergistic effects between several biotic and abiotic factors influence community assembly. My results suggest that non-random allopatric patterns of niche occupancy observed in these ant communities are better explained by high levels of aggression displayed between pairs of species that seldom co-occur, though I was unable to falsify the hypothesis that habitat preference also plays a role in determining their distribution and co-occurrence patterns. The modification of behaviour by external factors – either natural (e.g. temperature) or human mediated (e.g. pesticide exposure) – likely has broad effects on population and community dynamics and on patterns of species co-existence.</p>

Disentangling factors that assemble New Zealand's ant communities

<p>Several biotic and abiotic stressors can influence community assembly. The negative co-occurrence patterns observed within many communities, for example, may derive either from behavioural similarities (e.g. species displaying high aggression levels towards each other) or habitat preference. I evaluated the role of several stressors that may shape New Zealand’s ant communities. First, I investigated (in chapter 2) the co-occurrence patterns of two native ant communities located within transitional grassland-forest habitats. I also monitored the temperature variation in these habitats over a one-year period. I found that grasslands are exposed to higher temperature variation than forest habitats. I also found that some ants are mostly associated with forest habitats and others with grasslands. Using null models to examine these communities, I found evidence that two ant species (Monomorium antarcticum and Prolasius advenus) exhibit negative co-occurrence patterns. In the reminder of my thesis I developed a series of laboratory-based experiments to examine the processes that could explain the co-occurrence patterns that I observed in these ant communities. In chapter 3, I subjected heterospecific groups of ants to interactions in controlled conditions. I asked if interspecific aggression predict the survival probability and co-occurrence patterns described in chapter 2. My results demonstrated that aggression predicted the survival probability of interacting ant species and their co-occurrence patterns. I argued that aggressive behaviour might reflect the risks imposed by competitors. Differences in aggression may thus be a key factor influencing sympatric and allopatric co-occurrence patterns of these ant communities. In chapter 4, I tested the hypotheses that arrival sequence and diet influence the strength of interactions between colonies of two species that exhibited negative co-occurrence patterns (P. advenus and M. antarcticum). When arriving first, P. advenus displayed increased aggression and M. antarcticum a defensive reaction. The adoption of a defensive reaction by M. antarcticum increased their colony survival probability. Changes in carbohydrate and protein availability modulated colony activity rates of both species. These results indicate that arrival sequence can modulate the territorial behaviour displayed by interacting species in situations of conflict. Also, I showed that these ant species adjust their foraging activity rates in according to their diet, but different species do so differently. In chapter 5, I expanded the scope of chapter 4 and asked if aggression and foraging behaviour of P. advenus and M. antarcticum change in different conditions of temperature, diet and group size. For both ant species, changes in temperature had stronger effects on small than large colonies. Small groups of M. antarcticum displayed higher foraging activity at lower temperatures. Conversely, small groups of P. advenus displayed higher foraging activity at high temperatures. Also, small M. antarcticum colonies displayed increased aggression and significantly reduced the size of large P. advenus colonies, regardless of temperature and diet. These results suggest that P. advenus and M. antarcticum perform differently at different temperatures. Furthermore, I demonstrated that the persistence of these small colonies might be related to their ability to modulate foraging activities and interspecific aggression according to the environment. I also investigated (in chapter 6) the effects of a neurotoxic pesticide (neonicotinoid) on a native (M. antarcticum) and an invasive ant (Linepithema humile). I tested whether sublethal contamination with a neonicotinoid affects foraging, fitness and the outcome of interspecific interactions between these ants. Overall, pesticide exposure increased aggression of the invasive ant and reduced the aggression of the native species. Importantly, non-exposed individuals of the invasive species subjected to interactions against exposed natives were less aggressive, but more likely to survive. These results suggest that the modification of the physicochemical environment by pesticide contamination could change the dynamics of communities and influence invasion success. Overall, this thesis highlights that synergistic effects between several biotic and abiotic factors influence community assembly. My results suggest that non-random allopatric patterns of niche occupancy observed in these ant communities are better explained by high levels of aggression displayed between pairs of species that seldom co-occur, though I was unable to falsify the hypothesis that habitat preference also plays a role in determining their distribution and co-occurrence patterns. The modification of behaviour by external factors – either natural (e.g. temperature) or human mediated (e.g. pesticide exposure) – likely has broad effects on population and community dynamics and on patterns of species co-existence.</p>