Human-induced Habitat Modification Research Articles

The potential range and future distribution of the endangered lizard Darevskia clarkorum in the Caucasus Biodiversity Hotspot under climate change scenarios

The Clarks’ Lizard, Darevskia clarkorum is endemic to the Caucasian biodiversity hotspot, remarkable in terms of biogeography and evolutionary history in the Palearctic Realm. The purpose of this study is to evaluate the current distribution pattern of this species as well as its possible changes under various future climate scenarios. Fieldwork was conducted in Northeastern Anatolia and the Caucasus between 2019 and 2022, and 64 occurrence records and five bioclimatic variables were analysed using Ecological Niche Modeling (ENM) software. The annual temperature range is the most important variable influencing the distribution of this lizard species. The results showed that potential habitats for the Clarks’ Lizard are wider than its present distribution. It is predicted that under current climate change scenarios, this species’ range will be much more restricted than it is now. With rising greenhouse gas levels and solar radiation rates, the range of this species is expected to shift from northern Anatolia to the Caucasus mountainous areas, and would likely shrink in future. The remaining habitats of this lizard species may be significantly impacted by climate change and human-induced habitat modification.

Sharing space between native and invasive small mammals: Study of commensal communities in Senegal.

Urbanization processes are taking place at a very high rate, especially in Africa. At the same time, a number of small mammal species, be they native or invasive, take advantage of human-induced habitat modifications. They represent commensal communities of organisms that cause a number of inconveniences to humans, including potential reservoirs of zoonotic diseases. We studied via live trapping and habitat characterization such commensal small mammal communities in small villages to large cities of Senegal, to try to understand how the species share this particular space. Seven major species were recorded, with exotic invasive house mice (Mus musculus) and black rats (Rattus rattus) dominating in numbers. The shrew Crocidura olivieri appeared as the main and more widespread native species, while native rodent species (Mastomys natalensis, M. erythroleucus, Arvicanthis niloticus and Praomys daltoni) were less abundant and/or more localized. Habitat preferences, compared between species in terms of room types and characteristics, showed differences among house mice, black rats and M. natalensis especially. Niche (habitat component) breadth and overlap were measured. Among invasive species, the house mouse showed a larger niche breadth than the black rat, and overall, all species displayed high overlap values. Co-occurrence patterns were studied at the global and local scales. The latter show cases of aggregation (between the black rat and native species, for instance) and of segregation (as between the house mouse and the black rat in Tambacounda, or between the black rat and M. natalensis in Kédougou). While updating information on commensal small mammal distribution in Senegal, a country submitted to a dynamic process of invasion by the black rat and the house mouse, we bring original information on how species occupy and share the commensal space, and make predictions on the evolution of these communities in a period of ever-accelerating global changes.

No evidence from long-term analysis of yellowfin tuna condition that drifting fish aggregating devices act as ecological traps

Human-induced habitat modifications can severely impact the biology and behavior of wild species. Drifting fish aggregating devices (DFADs), used by industrial purse-seine tropical tuna fisheries, significantly increased the number of floating objects found in the open ocean, with which tropical tuna associate. This habitat change has raised concerns over the risk of modifying the behavior and altering the biology of tuna and other associated species (the so-called ecological trap hypothesis). Relying on a time-series from 1987-2019 of more than 25000 length-weight samples collected in the western Indian Ocean, we reject the hypothesis that the body condition (Le Cren’s relative condition factor, Kn) of yellowfin tuna Thunnus albacares decreased concurrently with the increased number of DFADs. This result suggests the absence of negative long-term impacts of DFADs on the condition of tuna. As other factors may have counteracted possible negative effects of DFADs, we recommend long-term monitoring of the habitat along with biological and behavioral parameters of tunas to detect any critical change.

Biodiversity significance of small habitat patches: More than half of Indian bird species are in academic campuses

Habitat loss, fragmentation, and land-use changes threaten global biodiversity, and human needs are increasingly compromising the functional role of protected areas. Therefore, finding opportunities to conserve biodiversity within the human-modified landscape is crucial. Ecologists have begun paying attention to fragments of biodiversity habitats in the urban landscapes in the past few decades. Of these, academic campuses offer a unique opportunity to evaluate such fragments due to well-preserved green spaces within the campuses and maintenance of biodiversity data. We studied the scope of academic campuses in India for their biodiversity potential vis-à-vis their ability to retain the habitat for native biodiversity. We used bird richness as a surrogate to biodiversity as they are the most widely monitored species group. Academic campuses (n = 335) in India reported 779 bird species, with an average of 88 species per campus. The species included five critically endangered, seven endangered, 17 vulnerable, and 33 near-threatened species. Several campuses worldwide have held intact natural habitats for centuries. The campuses in India underwent human-induced habitat modification significantly less than their surrounding landscape in last one decade. The academic campuses globally could prove hugely beneficial in securing a wide variety of species in relatively small land areas. While our study was restricted to academic campuses, non-academic campuses such as the army, industrial and private establishments could further add to such spaces. The campuses could also serve as living repositories and evolutionary labs for plant and small animal species that remain isolated due to fragmentation.

The Boar War: Five Hot Factors Unleashing Boar Expansion and Related Emergency

The recent and ever-growing problem of boar (Sus scrofa forms including wild boar, hybrid and feral pig) expansion is a very complex issue in wildlife management. The damages caused to biodiversity and the economies are addressed in different ways by the various countries, but research is needed to shed light on the causal factors of this emergency before defining a useful collaborative management policy. In this review, we screened more than 280 references published between 1975–2022, identifying and dealing with five hot factors (climate change, human induced habitat modifications, predator regulation on the prey, hybridization with domestic forms, and transfaunation) that could account for the boar expansion and its niche invasion. We also discuss some issues arising from this boar emergency, such as epizootic and zoonotic diseases or the depression of biodiversity. Finally, we provide new insights for the research and the development of management policies.

Plant diversity drives responses of gall-inducing insects to anthropization in Neotropical savannas

Human-induced habitat modification is among the main factors that threaten biodiversity on the planet. For highly specialized herbivorous insects, such as galling insects, anthropogenic disturbances that affect plants can have great effects on insects. In this sense, in the present study, we investigated the diversity of host plants and gall-inducing insects in anthropized and preserved remnants of Neotropical savannas in the Brazilian Cerrado. Sampling was performed in 30 plots (10 × 10 m) distributed in six study areas. Of these total, fifteen plots were in areas with anthropized vegetation and fifteen plots in areas with preserved vegetation. Overall, we recorded 67 species of gall-inducing insects and 39 species of host plants. We found that the diversity of both host plant species and gall-inducing insects differed significantly between areas, being higher in preserved plots than in anthropized plots. Our results revelated that changes in the species richness and composition of gall-inducing insects from preserved environments to anthropized environments were mediated by changes in the richness and composition of the plant species, respectively. Our study stands out as the first to demonstrate that plant diversity drives responses of gall-inducing insects to human disturbance in Neotropical savannas. Our findings indicate that the preservation of natural vegetation is important for the conservation of plant assemblages and their gall-inducing insects in urban environments.

Disease driven extinction in the wild of the Kihansi spray toad, Nectophrynoides asperginis

ABSTRACT The Kihansi spray toad, Nectophrynoides asperginis, became extinct in the wild despite population monitoring and conservation management of its habitat in the Kihansi gorge, Tanzania. Previous investigations have indicated human induced habitat modification, predators, pesticides and disease as possible causes of a rapid population decline and the species extirpation. Here, we systematically investigate the role of disease in the extinction event of the wild toad population. The amphibian chytrid fungus, Batrachochytrium dendrobatidis, was detected in spray toads that died during the extinction event and subsequently in other amphibian species in Kihansi Gorge and the adjacent Udagaji Gorge, but not in any toads collected prior to this. Following the population decline, the remaining spray toad population gradually disappeared over a nine-month period. We demonstrate how demographic (rare, low fecundity, high elevation species) and behavioural (congregate in high densities) attributes predisposed the spray toads to chytridiomycosis, as a result of B. dendrobatidis infections, and how epidemic disease could have been exacerbated by altered environmental conditions in the spray wetlands. Our results show that chytridiomycosis was the proximate cause of extinction in the wild of N. asperginis. This represents the first known case of extinction by disease of an amphibian species in Africa. Captive breeding programs, in both the US and Tanzania, have been introduced in order to ensure the survival of the species and a reintroduction program is underway. However, we caution that chytridiomycosis remains an existing threat, which requires a comprehensive mitigation strategy before the desired conservation outcome of an established population of repatriated toads can be achieved.

Male-biased dispersal and the potential impact of human-induced habitat modifications on the Neotropical bat Trachops cirrhosus.

Gene flow, maintained through natal dispersal and subsequent mating events, is one of the most important processes in both ecology and population genetics. Among mammalian populations, gene flow is strongly affected by a variety of factors, including the species’ ability to disperse, and the composition of the environment which can limit dispersal. Information on dispersal patterns is thus crucial both for conservation management and for understanding the social system of a species. We used 16 polymorphic nuclear microsatellite loci in addition to mitochondrial DNA sequences (1.61 kbp) to analyse the population structure and the sex‐specific pattern of natal dispersal in the frog‐eating fringe‐lipped bat, Trachops cirrhosus, in Central Panama. Our study revealed that—unlike most of the few other investigated Neotropical bats—gene flow in this species is mostly male‐mediated. Nevertheless, distinct genetic clusters occur in both sexes. In particular, the presence of genetic differentiation in the dataset only consisting of the dispersing sex (males) indicates that gene flow is impeded within our study area. Our data are in line with the Panama Canal in connection with the widening of the Río Chagres during the canal construction acting as a recent barrier to gene flow. The sensitivity of T. cirrhosus to human‐induced habitat modifications is further indicated by an extremely low capture success in highly fragmented areas. Taken together, our genetic and capture data provide evidence for this species to be classified as less mobile and thus vulnerable to habitat change, information that is important for conservation management.

Genetic diversity and gene flow in a rare New Zealand skink despite fragmented habitat in a volcanic landscape

Anthropogenic habitat fragmentation often restricts gene flow and results in small populations that are at risk of inbreeding. However, some endangered species naturally occupy patchy habitat where local population extinction and recolonization are normal. We investigated population fragmentation in the range-restricted New Zealand small-scaled skink (Oligosoma microlepis), documenting changes in habitat occupancy and analyzing mitochondrial, microsatellite, and morphological variation sampled across the geographical range of the species (approximately 100 km2). Small-scaled skinks have a strong preference for rocky outcrops that exist in a mosaic of other habitat types. A metapopulation structure was indicated by both local extinction and colonization of new sites. We found relatively high mtDNA nucleotide site diversity within this narrow range (π = 0.004; 16S), evidence of inter-patch gene flow, and no statistical support for inbreeding. Gene flow was limited by geographical distance, although the existence of pasture between habitat patches apparently has not prevented skink dispersal. Generalized linear models indicated an association between body size and location suggesting a local environmental influence on phenotype. Prior to human-induced habitat modification, native forest probably separated preferred sites and, less than 2000 years ago, volcanic activity devastated much of the area currently occupied by O. microlepis. This skink appears able to re-establish populations if other human-linked factors such as agricultural intensification and introduced predators are limited. Although in contrast to expectations for a scarce and localized species living in a highly modified landscape, this lizard may have previously adapted to a dynamic, mosaic environment mediated by volcanism.

Responses of ghost crabs to habitat modification of urban sandy beaches

Sandy beaches in highly urbanised areas are subject to a wide range of human impacts. Ghost crabs are a commonly used ecological indicator on sandy beaches, as they are key consumers in these systems and counting burrow openings allows for rapid assessment of population size. This study assessed the pressures of urbanisation on sandy beaches in the highly urbanised estuary of Sydney Harbour. Across 38 beaches, we examined which physical beach properties, management practices and human induced habitat modification best predicted ghost crab distributions. Of all variables measured, the frequency of mechanical beach cleaning was the most important predictor of crab abundance, with low burrow densities at the highest cleaning frequency and the highest densities at beaches cleaned at the intermediate frequency (≤3 times per week). These results indicate that ghost crab populations in Sydney Harbour are more robust to the impacts of urbanisation than previously thought.

Conservation status affects elevational gradient in bird diversity in the Himalaya: A new perspective

Understanding diversity patterns along altitudinal gradients, and their underlying causes are important for conserving biodiversity. Previous studies have focused on climatic, energetic, and geographic variables (e.g., mid-domain effects), with less attention paid to human-induced habitat modifications. We used published data of bird distributions along an elevational gradient (0–4900 m) in the Nepalese Himalaya and interpolated species presence between elevational limits. The relationship between species richness and environmental variables was analyzed using generalized linear models. A low plateau relationship between bird richness and elevation was observed, with a main peak at intermediate elevations (2800 m). Across the total gradient, interpolated bird species richness had a unimodal relationship to maximum monthly precipitation and a linear response to seasonal variation in temperature, proportion of forest cover, and proportion of protected area. In lower elevations (0–2800 m), interpolated species richness had a positive and linear response to the proportion of Ramsar sites and a unimodal response to habitat heterogeneity. At higher elevations (2900–4900 m), interpolated bird richness had a positive linear response to monthly variation in temperature and a negative linear response to proportion forest cover. We conclude that factors related to human management are important drivers of elevational gradients in bird species richness.

Does Human-Induced Habitat Modification Influence the Impact of Introduced Species? A Case Study on Cavity-Nesting by the Introduced Common Myna (Acridotheres tristis) and Two Australian Native Parrots

Introduced species pose a major threat to biodiversity across the globe. Understanding the impact of introduced species is critical for effective management. Many species around the world are reliant on tree cavities, and competition for these resources can be intense: threatening the survival of native species. Through the establishment of 225 nest boxes, we examined the relationship between tree density and the abundance and nesting success of three bird species in Canberra, Australia. The common myna (Acridotheres tristis) is an introduced species in Australia, and the crimson rosella (Platycercus elegans) and eastern rosella (Platycercus eximius) are native species. We then investigated the impact of common myna nest box occupation on crimson rosella and eastern rosella abundance. Tree density significantly influenced the abundance and cavity-nesting of all three species. Common myna abundance (birds per square kilometer) was greatest at low tree density sites (101.9 ± 22.4) and declined at medium (45.4 ± 10.1) and high (9.7 ± 3.6) tree density sites. The opposite pattern was observed for the crimson rosella, with greater abundance (birds per square kilometer) at high tree density sites (83.9 ± 9.3), declining over medium (61.6 ± 6.4) and low (31.4 ± 3.9) tree density sites. The eastern rosella was more abundant at medium tree density sites (48.6 ± 8.0 birds per square kilometer). Despite the strong influence of tree density, we found a significant negative relationship between common myna nest box occupancy and the abundance of the crimson rosella (F 1,13 = 7.548, P = 0.017) and eastern rosella (F 1,13 = 9.672, P < 0.001) at some sites. We also observed a slight increase in rosella nesting interruptions by the common myna at lower tree densities (high: 1.3% ± 1.3, medium: 6.6% ± 2.2, low: 12.7% ± 6.2), although this increase was not statistically significant (F 2,40 = 2.435, P = 0.100). Our study provides the strongest evidence to date for the negative impact of the common myna on native bird abundance through cavity-nesting competition. However, due to the strong influence of habitat on species abundance and nesting, it is essential to investigate the impacts of introduced species in conjunction with habitat variation. We also suggest one component of introduced species management could include habitat restoration to reduce habitat suitability for introduced species.

Behavioural and genetic interactions between an endangered and a recently-arrived hummingbird

The invasion or expansion of non-native species into new geographic areas can pose a major threat to the conservation of biodiversity. These threats are augmented when the newly-arrived species interacts with native species that are already threatened by other ecological or anthropogenic processes. Potential interactions can include both competition for scarce resources and reproductive interference, including hybridisation. Understanding the dynamics of these interactions forms a crucial component of conservation management strategies. A recent contact zone occurs in the north of Chile between the endangered Chilean woodstar (Eulidia yarrellii) and the closely-related and recently-arrived Peruvian sheartail (Thaumastura cora), which expanded its range from Peru into Chile during the 1970s. We characterised the interactions between the species by combining population size estimates with molecular, morphological and behavioural data. We show that a low degree of hybridisation, but not introgression, is occurring between the two species. Despite interspecific morphological similarities, behavioural observations indicate that food niche overlap between the species is relatively low, and that the dietary breadth of sheartails is larger, which may have aided the species’ range expansion. Finally, woodstars dominate the sheartails in male–male territorial interactions. However, potentially increased energetic costs for woodstars associated with frequent territorial chases and courtship displaying with sheartails may exacerbate the effects of other threats on woodstar viability, such as human-induced habitat modification. This study highlights the value of implementing multidisciplinary approaches in conservation biology to gain a more complete understanding of interactions between recently-arrived and endangered species.

Current distribution and ecology of the critically endangered Valencia letourneuxi in Greece

AbstractThe current population status of the critically endangered Greek valencia Valencia letourneuxi (Sauvage, 1880), is presented, based on a thorough survey of low-altitude aquatic systems of Western Greece. The species’ historical geographical range appears to have been reduced, with the westernmost and southernmost populations being currently extinct or near extinction respectively, and the remaining ones in a vulnerable state. According to univariate and multivariate analysis, V. letourneuxi exhibits habitat specificity, with a strong affinity towards spring-fed wetlands with clear waters and rich surface vegetation, being thus vulnerable to human-induced habitat modifications and hydrological changes. The impact of the above threats, as well as of the introduction of alien species such as the mosquitofish Gambusia holbrooki is discussed.

Habitat use by platypus (Ornithorhynchus anatinus) in a modified Australian Wet Tropics catchment, north-eastern Queensland

The habitat affiliations of platypus (Ornithorhynchus anatinus) were investigated in the upper Barron River and its tributaries, a modified Wet Tropics catchment in north-eastern Queensland, Australia. A habitat assessment was carried out at 46 sites, and a visual monitoring survey was used to determine whether platypus were present at these sites. Habitat assessment of riparian and in-stream parameters included an evaluation of factors known to influence platypus populations: disturbance level, stream depth and width, riparian continuity, the amount of overhanging vegetation, bare soil along banks, large woody debris, weeds, pool and riffle area and substrate types. Sites where platypus sightings occurred were characterised by a minimum channel width of 3.8 m and slow-flowing pools with depths of 0.49–2.0 m. These findings concur with platypus habitat preferences as described in other regions, although some in-stream and riparian factors considered as important components of platypus habitat in other studies (riparian continuity, large woody debris, undercut banks and coarse stream substrate) were not associated with the presence of platypus in this study. This study represents the first investigation of the influence of human-induced habitat modification on platypus affiliations in an Australian Wet Tropics river system.

MRNA Translation

Ambient protein levels are under coordinated control of transcription, mRNA translation, and degradation. Whereas transcription and degradation mechanisms have been studied in depth in renal science, the role of mRNA translation, the process by which peptide synthesis occurs according to the genetic code that is present in the mRNA, has not received much attention. mRNA translation occurs in three phases: Initiation, elongation, and termination. Each phase is controlled by unique eukaryotic factors. In the initiation phase, mRNA and ribosomal subunits are brought together. During the elongation phase, amino acids are added to the nascent peptide chain in accordance with codon sequences in the mRNA. During the termination phase, the fully synthesized peptide is released from the ribosome for posttranslational processing. Signaling pathways figure prominently in regulation of mRNA translation, particularly the phosphatidylinositol 3 kinase-Akt-mammalian target of rapamycin pathway, the AMP-activated protein kinase-tuberous sclerosis complex protein 1/tuberous sclerosis complex protein 2-Rheb pathway, and the extracellular signal-regulated kinase 1/2 type mitogen-activated protein kinase signaling pathway; there is significant cross-talk among these pathways. Regulation by mRNA translation is suggested when changes in mRNA and protein levels do not correlate and in the setting of rapid protein synthesis. Ongoing work suggests an important role for mRNA translation in compensatory renal growth, hypertrophy and extracellular matrix synthesis in diabetic nephropathy, growth factor synthesis by kidney cells, and glomerulonephritis. Considering that mRNA translation plays an important role in cell growth, development, malignancy, apoptosis, and response to stress, its study should provide novel insights in renal physiology and pathology.