Biology subjects

Senzaki, M.

Publications and source records attributed to Senzaki, M..

5 recordsLinked to original sources

bioRxiv2026

Human and pet multimodal cues intensify wildlife fear responses

Fear of humans can drive persistent changes in wildlife behavioural and life-history traits, with cascading effects on entire ecosystems. Human multimodal cues and pet cues may influence such fear, yet no study has tested how wildlife fear responses change when human acoustic cues and pet visual and acoustic cues are added to human visual cues. Filling this gap is important for managing outdoor activities for humans and pets while conserving wildlife. Here, using dogs as a representative pet, we tested the effects of human and dog visual and acoustic cues on fear responses of sika deer (Cervus nippon yesoensis) across an ~800 km2 area in northern Japan, using alert distance (AD) and flight initiation distance (FID). We measured both distances with an approaching surveyor alone and with additional cues. Analyses with 266 observations showed that AD was estimated at 80.0 m with the human visual cue alone, and dog barking increased AD by 18.4 m. FID was estimated at 57.1 m with the human visual cue alone, and the human voice and the dog decoy increased FID by 11.3 m and 8.5 m, respectively. These results demonstrate that both human multimodal cues and pet cues can increase wildlife fear responses, suggesting that dog walking may expose wildlife to concurrent predator-associated cues more consistently than occurs under natural conditions. Our finding that adding human acoustic cues increased FID, contrary to previous studies, suggests that animals may adjust the relative weighting of sensory cues depending on predator species. These findings highlight the importance of considering the combined effects of human and pet cues when managing recreation in sensitive areas, favouring targeted measures over blanket restrictions.

ecology↗

bioRxiv2026

The impacts of seventy years of changes in stopover habitats on the critically endangered Spoon-billed Sandpiper Calidris pygmaea

Natural habitat loss due to land use change is a major driver of global biodiversity loss. Human-created seminatural environments can function as artificial habitats for many species, partially offsetting these negative impacts. However, it remains unclear how species respond to the short- and long-term changes in both natural and artificial habitats, particularly for long-distance migratory species at stopover sites. We investigated how the globally endangered habitat specialist species, Spoon-billed Sandpipers Calidris pygmaea, responded to 70 years of changes in natural wetlands, sandy beaches, and artificial wetlands across stopover habitats in the Japanese Archipelago. We compiled historical observation records of the species from multiple sources and quantified the extent of these three habitat types from 1950 to 2020. Spoon-billed Sandpiper abundance consistently declined from the 1970s to the 2010s, with a particularly sharp decrease between the 1980s and the 1990s. While more than 50% of natural wetlands and sandy beaches have also been lost since 1950, we found that sandpiper abundance was lower at sites experiencing greater cumulative natural habitat loss. By contrast, changes in artificial wetland extent were not significantly associated with abundance, despite their temporal expansion peaking in the 1970s and subsequently declining. Our findings demonstrate that historical loss of natural stopover habitats have had lasting negative effects on local sandpiper populations, and the temporary expansion of artificial wetlands failed to compensate for these effects. This underscores the critical importance of preserving the networks of natural stopover habitats to sustain migration success, particularly for habitat specialists.

ecology↗

bioRxiv2023

Phylogenomics reveals the demography of reverse colonization in a rail species

AimIslands have recently been recognized as potential sources of biodiversity, challenging the traditional view that their small population sizes and low genetic diversity limit such roles. This raises the question of how insular genetic variation becomes incorporated into continental populations, contrary to expectations of unidirectional colonization. Here, we investigate whether and how island-derived genetic variation has influenced a continental population through population establishment and gene flow in a bird species where frequent trans-ocean dispersal is expected. LocationContinental East Asia (Russian Far East), Japanese Archipelago TaxonSwinhoes Rail (Coturnicops exquisitus) Materials and MethodsWe apply integrative phylogenomics to reconstruct the spatiotemporal history of the species. Colonization sequences and gene flow are inferred by comparing four different phylogenetic reconstruction methods, using mitochondrial sequences obtained by Sanger sequencing and genome-wide data obtained by genotyping by sequencing (MIG-seq). We assess a history of colonization and gene flow based on summary statistics, demographic trajectory inference by Stairway Plot2, demographic modeling by fastsimcoal2, and species distribution modeling. ResultsAnalyses collectively supported asymmetric gene flow from the island to the continental population, following divergence around the Middle Pleistocene. Post-divergence, the island maintained a large and stable population, while the continental population underwent a severe bottleneck, suggesting a significant evolutionary role of the island for the continental population. Additionally, evidence of recent re-establishment of the island by continental individuals indicates dynamic exchange and persistence within a continent-island metapopulation. Main conclusionsThe maintenance of insular genetic variation within a dynamic continent-island metapopulation may have enabled the island to act as a genetic and demographic reservoir for the continental population. Thus, continent-island metapopulation dynamics may be a key evolutionary pathway through which island populations contribute to continental genetic diversity.

evolutionary biology↗

bioRxiv2022

Intentional stocking undermines ecological stability

The past decades have witnessed efforts to unveil ecological risks associated with massive releases of captive-bred individuals ("stock enhancement"). Still, we may underestimate the negative impact because current schemes rarely consider the consequences of stock enhancement for the whole ecological community. Here, we use theory and long-term data of Japanese stream fish communities to show that stock enhancement undermines community stability. Our theory predicted that stock enhancement destabilizes community dynamics by facilitating competitive exclusion. Consistent with this prediction, fish communities showed greater temporal fluctuations and fewer species richness in rivers with the intensive stocking of hatchery masu salmon - a major freshwater resource in the region. Our findings paint a bleak picture for stock enhancement, reinforcing the recurrent calls for alternative management strategies. One Sentence SummaryLarge-scale releases of captive-bred organisms undermine the long-term persistence of ecological communities by disrupting the stable coexistence of competing species.

ecology↗

bioRxiv2022

Population-specific association of Clock gene polymorphism with annual cycle timing in stonechats

Timing is essential for survival and reproduction of organisms across the tree of life. The core circadian clock gene Clk has been implicated in annual timing and shows highly conserved sequence homology across vertebrates except for one variable region of poly Glutamine repeats. Clk genotype varies in some species with latitude, seasonal timing and migration. However, findings are inconsistent, difficult to disentangle from environmental responses, and biased towards high latitudes. Here we combine field data with a common-garden set up to study associations of Clk with latitude, migration and annual-cycle timing within the stonechat species complex with trans-equatorial distribution range. Including 950 individuals from nine populations with diverse migratory strategies. Gene diversity was lowest in resident African and Canary Island populations and increased with latitude, independently of migration distance. Repeat length and annual-cycle timing was linked in a population-specific way. Specifically, equatorial African stonechats showed delayed timing with longer repeat length for all annual-cycle stages. Our data suggest that at low latitudes with constant photoperiod, Clk genotype might orchestrate a range of consistent, individual chronotypes. In contrast, the influence of Clk on annual-cycle timing at higher latitudes might be mediated by its interactions with genes involved in (circadian) photoperiodic pathways.

genetics↗