The mallard take-over — Ducks Unlimited Canada

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22/10/2023, 19:20 The mallard take-over — Ducks Unlimited Canada https://www.ducks.ca/stories/iwwr/the-mallard-take-over/ 1/6 Shop Donate Now Story / IWWR± Science± Waterfowl The mallard take±over Could the prevalence of mallard±like traits in today’s waterfowl go back thousands of years? September ±±² ±³´µ  About Us Stories Conservator Magazine News & Media Resources Stay informed FAQ Our Work  Places  How to Help  Is mallard hybridization less common than we once thought? ©Ian McCausland Flecks of green on the heads of Mexican ducks¶ A white bar spanning the wing of a North American black duck¶ A mottled duck with black tail feathers¶ For years² when waterfowl biologists spotted ducks with mallard·like traits like these² they dismissed them as a hybrids¶ After all² with mallard populations straddling ´± million and spanning much of the continent² it was plausible that they were mating with other duck species² and in the process² passing on some of their mallard characteristics to their offspring¶   Stories View All Stories

22/10/2023, 19:20 The mallard take-over — Ducks Unlimited Canada https://www.ducks.ca/stories/iwwr/the-mallard-take-over/ 2/6 It was a trend that concerned some wildlife managers² who worried mallards’ amorous intermingling with other species would decrease diversity and that smaller populations of birds would soon become genetically extinct¶ Species like the Mexican duck² whose population numbers rest between ¸³²³³³ to ¹³²³³³¶ But what if mallard hybridization is less common than earlier thought² or there are “built in” ways that ducks ºor other species» lessen the effect of hybridization? It’s a question Philip Lavretsky set out to answer¶ Lavretsky² an assistant professor of biological sciences at the University of Texas El Paso² has two passions¼ genetics and waterfowl¶ For the past seven years² he’s married those interests to learn more about North American ducks¶  

22/10/2023, 19:20 The mallard take-over — Ducks Unlimited Canada https://www.ducks.ca/stories/iwwr/the-mallard-take-over/ 3/6  

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22/10/2023, 19:20 The mallard take-over — Ducks Unlimited Canada https://www.ducks.ca/stories/iwwr/the-mallard-take-over/ 4/6 It’s a point of pride among waterfowlers and birders to spot a duck and identify it based on its appearance¶ Tell·tale features like plumage² body and ﬂight composition tell us if we’re looking at a blue·winged teal or gadwall¶ But sometimes² identifying waterfowl can be diﬃcult² especially if they have traits that are indicative of two different species¶ Although geneticists had some success differentiating distantly related species² they weren’t having much luck drawing a distinction between more closely related species² like those within the mallard complex¶ The mallard complex refers to a group of closely linked species of mallard·like ducks found around the world and believed to be decedent from a species originally from Africa¶ “You could see in your hand what ½mallard·like¾ species the feather had come from¶ There are clear phenotypic differences¶ But you’d look at the genome and you just couldn’t find it²” says Lavretsky¶ Present in nearly every living organism² genomes are complete sets of genetic instructions² made up of deoxyribonucleic acid ºDNA»¶ “Picture this² ducks have genomes that say they’re a duck¶ And across the board² genetically² they’re very similar¶ But then² there’s genes that differentiate them¶ Genes that make a mallard’s head green and that give a cinnamon teal a blue beak²” says Lavretsky¶ While he knew genes causing these differences had to exist² in ±³³¿ they still hadn’t been found¶ In ±³³¿² Lavretsky² then a PhD student at Wright State University tried to solve that problem using new genomic techniques¶ He documented his work in a ±³´¹ research article that DUC recognized with the Institute for Wetland and Waterfowl Research ºIWWR» student publication award¶ In his work² Lavretsky collected and analyzed genetic samples from mallards and Mexican ducks¶ According to the American Ornithologist’s Union ºAOU»² Mexican ducks are a mallard subspecies¶ In the world of taxonomy this means that Mexican ducks are too similar to mallards to be considered their own species² but different enough that they can’t go by the same name¶ Through research² Lavretsky discovered that while Mexican ducks are almost genetically identical to mallards² there’s an important divergence in the Z chromosome¶ It was a ground·breaking discovery¶ Avian species² like humans² have two sex chromosomes¶ But unlike humans² who have X and Y sex chromosomes² birds have Z and W sex chromosomes¶ According to the Haldane rule² proposed by British evolutionary biologist John Haldane in ´¿±±² the earliest signs of speciation ºthe evolutionary process that leads to the creation of new species from existing ones» begin with a divergence in the sex chromosome¶ “We’re repeatedly finding similar patterns of Z·sex chromosome divergence when comparing other species within the mallard group² as well as in other closely related waterfowl groups²” says Lavretsky¶ And so while Mexican ducks share a genetic history with mallards² over time they’re becoming increasingly unique² as reﬂected in their darker² all brown plumage¶ “What we’re finding² in my opinion² is that these ½mallard·like¾ traits are part of the genome and it’s a random effect…a result of recent ancestry with the mallard²” says Lavretsky¶ “It’s not always easy to assume that certain traits are indicative of hybrids² as these can be shared within the group for some time²” he adds¶ But that doesn’t mean hybridization isn’t happening¶ “We know it occurs²” he says¶ It’s the frequency at which it happens that his findings call into question¶ To further his research² Lavretsky is now working towards publishing data that indicates there are tell·tale markers in the genome that reveal if a bird is a hybrid¶   By collecting and analyzing genetic samples from mallards and Mexican ducks ºpictured» researchers discovered that while Mexican ducks are almost genetically identical to mallards² there’s an important divergence in the Z chromosome¶ ©Philip Lavretsky

22/10/2023, 19:20 The mallard take-over — Ducks Unlimited Canada https://www.ducks.ca/stories/iwwr/the-mallard-take-over/ 5/6 Boreal Forest² IWWR² Prairie Pothole Region² Science² Wetlands Cutting±edge climate data reveal the nature of change in tomorrow’s landscapes trueDUC researchers collaborate on landscape·level climate questions for wetlands IWWR² Science² Water² Wetlands The power of small wetlands for clean water trueNew DUC research quantifies the role of restored wetlands in capturing phosphorus in agricultural watersheds¶ Conservator² IWWR² Science Citizen science gone wild trueHow can you contribute to conservation research? The answer is at your fingertips¶ “By using genetic techniques that allow access to larger portions of a genome² we are able to assess which traits are associated with genetically assigned hybrids¶ This refines our understanding and identification of plumage characteristics that are truly indicative of hybrids²” he says¶ A method developed by his colleagues and published recently in Wildlife Society Bulletin º“Is it a mottled duck? The key is in the feathers”»² allowed the researchers to correctly identify nearly ¿³ per cent of the mallards² mottled ducks² and their hybrids they examined¶ Moreover² they found that a trait ºpresence/absence of white on the wing» that at one time was used to identify hybrids is in fact a characteristic found in approximately ´³ per cent of the Florida mottled duck population and not necessarily linked with hybrid status¶ Combined with Lavretsky’s work on speciation in Mexican ducks² the findings could have important implications in the conservation realm¶ “We’ll be able to understand if there are certain regions that are more impacted by hybridization² and if so² we can decide what to do to mitigate that²” says Lavretsky¶ That interests DUC’s director of conservation science² David Howerter¶ “DUC has a philosophy to try and maintain the diversity of species out there¶ So understanding the processes is important²” he says¶ Studying speciation in waterfowl is a relatively new field that began in the late ´¿À³s¶ And looking at duck DNA is even more recent¶ “A lot of work with mitochondrial DNA was undertaken in the ´¿¿³s¶ The problem was that it was continuously inconclusive²” says Lavretsky¶ However² as the science around genetics continues to evolve and become more affordable² he sees it gaining importance¶ “It’s hard to decipher and understand genetics² but the wildlife world can greatly benefit from what we’re able to do with the genomic perspective¶ We can ask a lot of question that translate to work on the ground²” says Lavretsky¶ Philip Lavretsky is one of two recipients of the ±³´¹ IWWR Student Publication Award¶ This award is given to raise awareness of the IWWR student program² reward students for successfully publishing their research² and to recognize publications that make a significant contribution to waterfowl and wetland research¶ Read These Stories Next Read more stories  

22/10/2023, 19:20 The mallard take-over — Ducks Unlimited Canada https://www.ducks.ca/stories/iwwr/the-mallard-take-over/ 6/6 Support us We need your help to conserve water² wetlands² and wildlife for the generations of tomorrow Footnotes Connect with us      Questions? Call³ ´ À³³ µµ¹·DUCK ºÁÀ±¹» Ducks Unlimited Canada PO Box ´´µ³ Stonewall² Manitoba² Canada R³C ±Z³ © ±³±Á Ducks Unlimited Canada Privacy Policy Terms of Use Make a one±time donation  Make a monthly donation  Give in Celebration  Give in Memoriam  Get involved  Leave your Legacy  Contact Us  Careers  Whistleblowers  Volunteer Login  Director Portal  News & Media   

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