Genetic analyses reveal limited dispersal and recovery potential in the large freshwater crayfish Euastacus armatus from the southern Murray–Darling Basin

2017 ◽  
Vol 68 (2) ◽  
pp. 213 ◽  
Author(s):  
Nick S. Whiterod ◽  
Sylvia Zukowski ◽  
Martin Asmus ◽  
Dean Gilligan ◽  
Adam D. Miller
Keyword(s):  
Gene Flow ◽  
Anthropogenic Impacts ◽  
Population Decline ◽  
Biological Traits ◽  
Freshwater Crayfish ◽  
Freshwater Species ◽  
Genetic Structuring ◽  
Murray Darling Basin ◽  
Murray River ◽  
Dispersal Limitations

Understanding dispersal traits and adaptive potential is critically important when assessing the vulnerability of freshwater species in highly modified ecosystems. The present study investigates the population genetic structure of the Murray crayfish Euastacus armatus in the southern Murray–Darling Basin. This species has suffered significant population declines in sections of the Murray River in recent years, prompting the need for information on natural recruitment processes to help guide conservation. We assessed allele frequencies from 10 polymorphic microsatellite loci across 20 sites encompassing the majority of the species’ range. Low levels of gene flow were observed throughout hydrologically connected waterways, but significant spatial autocorrelation and low migration rate estimates reflect local genetic structuring and dispersal limitations, with home ranges limited to distances <50-km. Significant genetic differentiation of headwater populations upstream of barriers imposed by impoundments were also observed; however, population simulations demonstrate that these patterns likely reflect historical limitations to gene flow rather than contemporary anthropogenic impacts. Dispersal limitations, coupled with its biological traits, suggest that local populations are vulnerable to environmental disturbance with limited potential for natural recolonisation following population decline. We discuss the implications of these findings in the context of managing the recovery of the species.

Genetic structure and phylogeography of freshwater shrimps (Macrobrachium australiense and Macrobrachium tolmerum): the role of contemporary and historical events

2009 ◽  
Vol 60 (6) ◽  
pp. 541 ◽  
Author(s):  
Suman Sharma ◽  
Jane M. Hughes
Keyword(s):  
Gene Flow ◽  
Population Expansion ◽  
Freshwater Species ◽  
River Systems ◽  
Genetic Structuring ◽  
Recent Population Expansion ◽  
Sea Levels ◽  
Coastal Streams ◽  
Limited Dispersal ◽  
Limited Gene Flow

Freshwater species are expected to show higher levels of genetic structuring than those inhabiting estuarine or marine environments because it is difficult for freshwater species to move between river systems. Previous genetic studies of freshwater species from coastal streams in south-east Queensland had proposed that several of these streams had a common confluence relatively recently, when sea levels were lower ~10 000 years bp. The present study was undertaken to test this idea using two freshwater shrimp species, Macrobrachium australiense and Macrobrachium tolmerum. In M. australiense, there was a major phylogeographical break in the middle of the Sunshine Coast region that was expected to be homogeneous because these creeks may have had a shared confluence before entering the sea, possibly because of extremely limited dispersal abilities compounded over many generations. In M. tolmerum, there was evidence of a recent population expansion and also some evidence of limited gene flow between sites. This is explained by recent colonisation of the area and limited gene flow between river systems, despite the ability of this species to survive in brackish water conditions. The present study shows that even species that are taxonomically very close and that co-occur in the same habitats can have vastly different population structures.

scholarly journals Providing factual support for efficient techniques of breeding tropical freshwater species

2020 ◽  
Vol 2020 (2) ◽  
pp. 94-105
Author(s):  
Lina Yurievna Lagutkina ◽  
Evgeniia Germanovna Kuzmina ◽  
Aliya Baimuratovna Akhmedzhanova ◽  
Anna Aleksandrovna Taranina ◽  
Victor Sergeevich Yasinskii ◽  
...  
Keyword(s):  
Raw Materials ◽  
Macrobrachium Rosenbergii ◽  
Climatic Conditions ◽  
Seeding Density ◽  
Maximum Effect ◽  
Freshwater Crayfish ◽  
Freshwater Species ◽  
Fish Farms ◽  
Experimental Works ◽  
Tropical Freshwater

The article describes the possibility to grow tropical freshwater crayfish Cherax quadricarinatus (Von Martens, 1868) and shrimp Macrobrachium rosenbergii (De Man, 1879) in the climatic conditions of the Astrakhan region during 3-5 months, with further wintering in the ponds of fish farms. To achieve the maximum effect of the semi-intensive and intensive cultivation conditions it is necessary to apply additional feeding, observe the norms of seeding density and the diets of crustaceans. In two series of experimental works conducted in 2019-2020 on the base of Astrakhan State Technical University and a small innovative enterprise Modern Fishbreeding Complex Sharapovsky there was studied the method of increasing the biological and aquaculture potential of fast-growing tropical freshwater crayfish and shrimps by adjusting feed diets, chilled wet feed, and native formula feed based on feed components of local raw materials. Salicornia perennans Willd, a halophyte plant, was introduced into the formulation for the first time. As a result of experimental works the recommendations on semi-intensive and intensive cultivation of tropical freshwater species have been formulated, the possibility of increasing biological and aquaculture productivity of grown objects has been considered, which is recorded in the fish-biological standards and general management processes.

scholarly journals Genetic Structuring Among Migratory Populations of the Black-Whiskered Vireo, with a Comparison to the Red-Eyed Vireo

The Condor ◽  
2001 ◽  
Vol 103 (3) ◽  
pp. 439-448
Author(s):  
Patrick W. Zwartjes
Keyword(s):  
Puerto Rico ◽  
Gene Flow ◽  
Random Amplified Polymorphic Dna ◽  
Florida Keys ◽  
The United States ◽  
Genetic Structuring ◽  
Vireo Olivaceus ◽  
La Florida ◽  
Southern Florida ◽  
Los Grupos

AbstractThe Black-whiskered Vireo (Vireo altiloquus) breeds from coastal southern Florida in the United States through the islands of the West Indies, and thus consists of several populations separated by large regions of uninhabitable space. I examined genetic variation within and among six migratory populations in the Florida Keys, Jamaica, and Puerto Rico, using random amplified polymorphic DNA (RAPD) markers and analysis of molecular variance (AMOVA). Calculations of variance components revealed that over 90% of the variance was among individuals; a significant portion also occurred among regional groups (Florida, Jamaica, and Puerto Rico). Variance between subpopulations within the regional groups was not significantly different from zero. This contrasts with the closely related Red-eyed Vireo (V. olivaceus) of continental North America, in which analyses of three widely separate geographic localities revealed that over 99% of the genetic variance was among individuals, with no significant variance detectable among localities. The greatest differences in V. altiloquus were detected between the Florida Keys populations and the populations from Jamaica and Puerto Rico; the latter two showed no significant differentiation. Estimates of gene flow from the AMOVA analog to Wright's F-statistics suggest that there is enough gene flow among regions to prevent differentiation by genetic drift. Although not strongly isolated, the Florida population of V. altiloquus is sufficiently differentiated to suggest reduced genetic exchange with the populations on Puerto Rico and Jamaica.Estructura Genética entre Poblaciones Migratorias de Vireo altiloquus con una Comparación con Vireo olivaceusResumen. Vireo altiloquus se reproduce desde la costa del sur de la Florida en los Estados Unidos hasta las islas de las Antillas, y por lo tanto presenta varias poblaciones separadas por extensas regiones de espacio no habitable. Examiné la variación genética dentro y entre seis poblaciones migratorias en los Cayos de la Florida, en Jamaica y en Puerto Rico, usando marcadores polimórficos de ADN amplificados al azar (RAPD) y análisis de varianza molecular (AMOVA). Los cálculos de los componentes de la varianza indicaron que más del 90% de la varianza se presentó entre individuos; una porción significativa también estuvo presente entre los grupos regionales (Florida, Jamaica y Puerto Rico). La varianza entre subpoblaciones dentro de grupos regionales no fue significativamente diferente de cero. Esto contrasta con los resultados para V. olivaceus de Norteamérica continental, donde los análisis de tres localidades alejadas revelaron que más del 99% de la varianza genética se registró entre individuos, sin varianza significativa detectable entre localidades. Las mayores diferencias en V. altiloquus fueron detectadas entre las poblaciones de los Cayos de la Florida y las poblaciones de Jamaica y Puerto Rico; las últimas dos no mostraron diferencias significativas. Las estimaciones de flujo génico a partir del AMOVA, análogo al estadístico F de Wright, sugieren que hay suficiente flujo génico entre las regiones para evitar diferenciación por deriva génica. Aunque no está muy aislada, la poblacion de V. altiloquus de la Florida se diferencia lo suficiente como para sugerir un intercambio génico reducido con las poblaciones de Puerto Rico y Jamaica.

scholarly journals Urban Sprawl, Food Subsidies and Power Lines: An Ecological Trap for Large Frugivorous Bats in Sri Lanka?

Diversity ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 94 ◽  
Author(s):  
José L. Tella ◽  
Dailos Hernández-Brito ◽  
Guillermo Blanco ◽  
Fernando Hiraldo
Keyword(s):  
Sri Lanka ◽  
Anthropogenic Impacts ◽  
Population Decline ◽  
Ecological Trap ◽  
Power Lines ◽  
Foraging Habitat ◽  
Urban Habitats ◽  
Flying Foxes ◽  
Food Subsidies ◽  
Urbanized Areas

Electrocution is one of the less known anthropogenic impacts likely affecting the bat population. We surveyed 925 km of overhead distribution power lines that supply energy to spreading urbanized areas in Sri Lanka, recording 300 electrocuted Indian flying foxes (Pteropus giganteus). Electrocutions were recorded up to 58 km from the nearest known colony, and all of them were in urbanized areas and very close ( X ¯ = 4.8 m) to the exotic fruiting trees cultivated in gardens. Predictable anthropogenic food subsidies, in the form of cultivated fruits and flowers, seem to attract flying foxes to urban habitats, which in turn become ecological traps given their high electrocution risk. However, electrocution rates greatly varied among the 352 power lines surveyed (0.00–24.6 indiv./km), being highest in power lines with four wires oriented vertically ( X ¯ = 0.92 indiv./km) and almost zero in power lines with wires oriented horizontally. Therefore, the latter design should be applied to projected new power lines and old vertically oriented lines in electrocution hotspots should be substituted. Given that flying foxes are key seed dispersers and pollinators, their foraging habitat selection change toward urban habitats together with high electrocution risk not only may contribute to their population decline but also put their ecosystem services at risk.

Abundance, distribution and reproduction of the Data-Deficient species (Squalus blainville) around Sardinia Island (central western Mediterranean Sea) as a contribution to its conservation

2021 ◽  
Vol 72 (1) ◽  
pp. 118 ◽  
Author(s):  
Martina Francesca Marongiu ◽  
Cristina Porcu ◽  
Andrea Bellodi ◽  
Rita Cannas ◽  
Pierluigi Carbonara ◽  
...  
Keyword(s):  
Population Decline ◽  
Temporal Trends ◽  
Reproductive Potential ◽  
Western Mediterranean ◽  
Biological Traits ◽  
Abundance Distribution ◽  
Western Mediterranean Sea ◽  
Fishery Data ◽  
Data Deficient

Data-Deficient (DD) species are currently under threat because of the paucity of information regarding their abundance, distribution and biological traits. In this study we analysed temporal trends and bioecological features of the DD shark, Squalus blainville. Biological and fishery data were collected through two different scientific surveys spanning 1994–2018 and commercial hauls around Sardinia Island (central western Mediterranean) from 2008 to 2018. The analysis of temporal trends based on abundance data revealed a significant population decline over time. The late attainment of maturity and low fecundity of S. blainville are suspected to have contributed to making it highly vulnerable to overfishing. No bathymetric segregation by sex and size was found. However, the almost exclusive presence of pregnant females south-west of Sardinia could be due to sexual spatial segregation. This is also supported by histological findings showing long-term sperm storage to ensure the persistence of the species when females and males are separated. The documented decline of this species, its low reproductive potential and similarities in the depth distribution of immature and mature individuals indicate the need for urgent protection plans for S. blainville in Sardinian waters.

scholarly journals Genetic Structure and Gene Flow in Red Foxes (Vulpes vulpes) in Scandinavia: Implications for the Potential Future Spread of Echinococcus multilocularis Tapeworm

2019 ◽  
Vol 9 (24) ◽  
pp. 5289
Author(s):  
Mari Hagenlund ◽  
Arne Linløkken ◽  
Kjartan Østbye ◽  
Zea Walton ◽  
Morten Odden ◽  
...  
Keyword(s):  
Gene Flow ◽  
Population Ecology ◽  
Wildlife Management ◽  
Echinococcus Multilocularis ◽  
Vulpes Vulpes ◽  
Red Fox ◽  
Emerging Diseases ◽  
Red Foxes ◽  
Genetic Structuring ◽  
High Level

Knowledge about the dispersal and gene flow patterns in wild animals are important for our understanding of population ecology and the connectedness of populations. It is also important for management relating to disease control and the transmission of new and emerging diseases. Our study aimed to evaluate the genetic structuring among comparative samples of red foxes in a small part of Scandinavia and to estimate the gene flow and potential directionality in the movements of foxes using an optimized set of microsatellite markers. We compared genetic samples of red foxes (Vulpes vulpes) from two areas in Sweden and two areas in Norway, including red fox samples from areas where the occurrence of the cyclophyllic tapeworm Echinococcus multilocularis has been documented, and areas without known occurrence of the parasite. Our results show a high level of gene flow over considerable distances and substantiates migration from areas affected with E. multilocularis into Norway where the parasite is not yet detected. The results allow us to better understand the gene flow and directionality in the movement patterns of red foxes, which is important for wildlife management authorities regarding the spread of E. multilocularis.

scholarly journals Scavenging by threatened turtles regulates freshwater ecosystem health during fish kills

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Claudia Santori ◽  
Ricky-John Spencer ◽  
Michael B. Thompson ◽  
Camilla M. Whittington ◽  
Thomas H. Burd ◽  
...  
Keyword(s):  
Water Quality ◽  
Ecosystem Health ◽  
Freshwater Ecosystems ◽  
Freshwater Ecosystem ◽  
Freshwater Species ◽  
Freshwater Turtles ◽  
Fish Kills ◽  
Murray Darling Basin ◽  
Ecological Implications ◽  
Mesocosm Experiments

Abstract Humans are increasing the frequency of fish kills by degrading freshwater ecosystems. Simultaneously, scavengers like freshwater turtles are declining globally, including in the Australian Murray–Darling Basin. Reduced scavenging may cause water quality problems impacting both ecosystems and humans. We used field and mesocosm experiments to test whether scavenging by turtles regulates water quality during simulated fish kills. In the field, we found that turtles were important scavengers of fish carrion. In mesocosms, turtles rapidly consumed carrion, and water quality in mesocosms with turtles returned to pre-fish kill levels faster than in turtle-free controls. Our experiments have important ecological implications, as they suggest that turtles are critical scavengers that regulate water quality in freshwater ecosystems. Recovery of turtle populations may be necessary to avoid the worsening of ecosystem health, particularly after fish kills, which would have devastating consequences for many freshwater species.

Weak genetic structuring suggests historically high genetic connectivity among recently fragmented urban populations of the scincid lizard, Ctenotus fallens

2015 ◽  
Vol 63 (4) ◽  
pp. 279 ◽  
Author(s):  
Josef Krawiec ◽  
Siegfried L. Krauss ◽  
Robert A. Davis ◽  
Peter B. S. Spencer
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Large Population ◽  
Geographic Distance ◽  
Genetic Erosion ◽  
Genetic Connectivity ◽  
Genetic Structuring ◽  
Low Genetic Diversity ◽  
Population Sizes

Populations in fragmented urban remnants may be at risk of genetic erosion as a result of reduced gene flow and elevated levels of inbreeding. This may have serious genetic implications for the long-term viability of remnant populations, in addition to the more immediate pressures caused by urbanisation. The population genetic structure of the generalist skink Ctenotus fallens was examined using nine microsatellite markers within and among natural vegetation remnants within a highly fragmented urban matrix in the Perth metropolitan area in Western Australia. These data were compared with samples from a large unfragmented site on the edge of the urban area. Overall, estimates of genetic diversity and inbreeding within all populations were similar and low. Weak genetic differentiation, and a significant association between geographic and genetic distance, suggests historically strong genetic connectivity that decreases with geographic distance. Due to recent fragmentation, and genetic inertia associated with low genetic diversity and large population sizes, it is not possible from these data to infer current genetic connectivity levels. However, the historically high levels of gene flow that our data suggest indicate that a reduction in contemporary connectivity due to fragmentation in C. fallens is likely to result in negative genetic consequences in the longer term.

A demographic framework for the adaptive management of the endangered arid-zone tree species Acacia peuce

2013 ◽  
Vol 61 (2) ◽  
pp. 89 ◽  
Author(s):  
S. Raghu ◽  
Catherine E. M. Nano ◽  
Chris R. Pavey
Keyword(s):  
Tree Species ◽  
Arid Zone ◽  
Anthropogenic Impacts ◽  
Population Decline ◽  
Extreme Rainfall ◽  
Vital Rates ◽  
Matrix Population Models ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Slow Growing

Slow-growing desert tree species pose unique conservation challenges; their demography is driven by rare stochastic climatic events, remoteness of populations makes monitoring difficult and, consequently, their management is often information-limited. In particular, the paucity of information on vital rates at a relevant temporal scale makes analyses of demography and population viability difficult. Our objective was to undertake a demographic analysis of the threatened arid-zone tree species (Acacia peuce F.Muell.) that is a model system in terms of being (1) a slow-growing desert tree species whose recruitment is limited to stochastic and rare extreme rainfall events, and (2) a species of conservation significance growing in a remote location where remoteness imposes limitations on conservation monitoring. Complementary analyses using pattern- and process-derived matrix population models, based on a dataset derived from a 30-year monitoring effort, verified that the smallest of the A. peuce populations would continue to grow under current environmental conditions. Population growth in this species is most influenced by the survival or adult and sapling stages. Stochastic demographic simulations revealed that climate change is likely to significantly elevate the risk of population decline, particularly in fragment stands. The long-term viability of A. peuce hinges on sustaining the survival rates of adult and sapling stages by managing stresses to individuals in these stages, and through minimising anthropogenic disturbance to populations during rare, stochastic and extreme rainfall events that trigger recruitment. Extending the current non-binding agreement enabling the use of fences to exclude cattle, and improved interpretative signage to raise awareness of anthropogenic impacts on this species will significantly aid conservation of this species. The integration of modelling, monitoring, and management within a demographic framework can facilitate efficient and effective conservation of slow-growing arid-zone tree species, despite the challenges imposed by remoteness.

Ceasefire: minimal aggression among Murray River crayfish feeding upon patches of allochthonous material

2015 ◽  
Vol 63 (2) ◽  
pp. 115 ◽  
Author(s):  
Danswell Starrs ◽  
Brendan C. Ebner ◽  
Christopher J. Fulton
Keyword(s):  
Leaf Litter ◽  
Aquatic Ecosystems ◽  
Plant Material ◽  
Woody Debris ◽  
Small Scale ◽  
Freshwater Crayfish ◽  
Fine Woody Debris ◽  
Trophic Pathways ◽  
Murray River ◽  
Freshwater Invertebrate

Transport and processing of allochthonous material is crucial for trophic pathways in headwater streams. Freshwater crayfish are known to affect and exploit the break-down of in-stream terrestrial plant material into detritus. We recorded Euastacus armatus (Murray River crayfish) individuals feeding on discrete patches of allochthonous material within an unregulated section of the Goodradigbee River, an upland stream in temperate Australia. Despite suggestions of aggressive territoriality, E. armatus were observed by remote and manual underwater filming to feed in non-aggressive aggregations on these piles of fine woody debris and leaf litter. On the basis of observations of 25 individuals found in the vicinity of the allochthonous patches, this population comprised mostly female individuals at smaller sizes of maturity than has been recorded for lowland populations of E. armatus. Our study confirms the importance of concentrated allochthonous food patches for detritivores, and points to the important trophic linkage between terrestrial and aquatic ecosystems via a widespread and iconic freshwater invertebrate. Moreover, these non-aggressive feeding aggregations of E. armatus challenge notions of aggression in this species that have been developed in small-scale aquarium studies.

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