Background: Evolutionary biology endeavours to explain biological diversity,and as such it is critical to develop an understanding of the adaptive and functional significance of trait variation.Spermatozoa exhibit rem...Background: Evolutionary biology endeavours to explain biological diversity,and as such it is critical to develop an understanding of the adaptive and functional significance of trait variation.Spermatozoa exhibit remarkable levels of morphological diversification.However,our understanding of the evolutionary causes and functional significance of this variation is limited,especially at the intraspecific level.Methods: We quantified variation in sperm morphology and performance between two subspecies of Long-tailed Finch(Poephila acuticauda acuticauda and P.a.hecki),a small grassfinch found in tropical northern Australia.Despite a zone of secondary contact,these subspecies are maintained as two distinct forms: P.a.acuticauda occurs in the western part of the species' range and has a yellow bill,while P.a.hecki exhibits a red bill and is found in the eastern part of the range.Results: We found small,but significant differences in sperm size between these subspecies(P.a.acuticauda had longer and narrower sperm than P.a.hecki),which was surprising given the recent evolutionary origins of these two taxa(i.e.0.3 million years ago).Additionally,both subspecies exhibited high values of between- and within-male variation in sperm morphology,though in the case of sperm midpiece length this variation was significantly lower in P.a.acuticauda relative to P.a.hecki.Conclusions: We suggest these observed differences in sperm morphology are the result of genetic drift and reflect historical processes associated with divergence between the eastern and western populations of these two subspecies.Finally,we discuss the potential implications of our findings for the process of population divergence and reproductive isolation.展开更多
Background:Modern ecosystems contain many invasive species as a result of the activity of acclimatisation societies that operated in the second half of the nineteenth century,and these species provide good opportuniti...Background:Modern ecosystems contain many invasive species as a result of the activity of acclimatisation societies that operated in the second half of the nineteenth century,and these species provide good opportunities for studying invasion biology.However,to gain insight into the ecological and genetic mechanisms that determine the rate of colonization and adaptation to new environments,we need a good understanding of the history of the introduced species,and a knowledge of the source population,timing,and number of individuals introduced is particularly important.However,any inaccuracies in the history of an introduction will affect subsequent assumptions and conclusions.Methods:Focusing on a single well-known species,the House Sparrow(Passer domesticus),we have documented the introduction into Australia using primary sources(e.g.acclimatisation records and newspaper articles).Results:Our revised history differs in a number of significant ways from previous accounts.Our evidence indicates that the House Sparrow was not solely introduced from source populations in England but also from Germany and most strikingly also from India—with the latter birds belonging to a different race.We also clarify the distinction between the number released and the number of founders,due to pre-release captive breeding programs,as well as identifying inaccuracies in a couple of well-cited sources with respect to the range expansion of the introduced populations.Conclusions:Our work suggests that caution is required for those studying introductions using the key sources of historical information and ideally should review original sources of information to verify the accuracy of published accounts.展开更多
基金the authority of the Macquarie University Animal Ethics Committee (ARA No. 2007/037)supported by Australian Research Council Discovery Project Grant DP0881019 (to SCG)+1 种基金supported by the Research Council of Norway Grant 196554Young Research Talent grant from the Research Council of Norway (230434/F20)
文摘Background: Evolutionary biology endeavours to explain biological diversity,and as such it is critical to develop an understanding of the adaptive and functional significance of trait variation.Spermatozoa exhibit remarkable levels of morphological diversification.However,our understanding of the evolutionary causes and functional significance of this variation is limited,especially at the intraspecific level.Methods: We quantified variation in sperm morphology and performance between two subspecies of Long-tailed Finch(Poephila acuticauda acuticauda and P.a.hecki),a small grassfinch found in tropical northern Australia.Despite a zone of secondary contact,these subspecies are maintained as two distinct forms: P.a.acuticauda occurs in the western part of the species' range and has a yellow bill,while P.a.hecki exhibits a red bill and is found in the eastern part of the range.Results: We found small,but significant differences in sperm size between these subspecies(P.a.acuticauda had longer and narrower sperm than P.a.hecki),which was surprising given the recent evolutionary origins of these two taxa(i.e.0.3 million years ago).Additionally,both subspecies exhibited high values of between- and within-male variation in sperm morphology,though in the case of sperm midpiece length this variation was significantly lower in P.a.acuticauda relative to P.a.hecki.Conclusions: We suggest these observed differences in sperm morphology are the result of genetic drift and reflect historical processes associated with divergence between the eastern and western populations of these two subspecies.Finally,we discuss the potential implications of our findings for the process of population divergence and reproductive isolation.
基金SCA was supported by Macquarie University Research Excellence Scholarships(No.2013077)SCG was supported by an Australian Research Council Future Fellowship(FT130101253)
文摘Background:Modern ecosystems contain many invasive species as a result of the activity of acclimatisation societies that operated in the second half of the nineteenth century,and these species provide good opportunities for studying invasion biology.However,to gain insight into the ecological and genetic mechanisms that determine the rate of colonization and adaptation to new environments,we need a good understanding of the history of the introduced species,and a knowledge of the source population,timing,and number of individuals introduced is particularly important.However,any inaccuracies in the history of an introduction will affect subsequent assumptions and conclusions.Methods:Focusing on a single well-known species,the House Sparrow(Passer domesticus),we have documented the introduction into Australia using primary sources(e.g.acclimatisation records and newspaper articles).Results:Our revised history differs in a number of significant ways from previous accounts.Our evidence indicates that the House Sparrow was not solely introduced from source populations in England but also from Germany and most strikingly also from India—with the latter birds belonging to a different race.We also clarify the distinction between the number released and the number of founders,due to pre-release captive breeding programs,as well as identifying inaccuracies in a couple of well-cited sources with respect to the range expansion of the introduced populations.Conclusions:Our work suggests that caution is required for those studying introductions using the key sources of historical information and ideally should review original sources of information to verify the accuracy of published accounts.
