{"id":64369,"date":"2025-09-18T14:58:20","date_gmt":"2025-09-18T13:58:20","guid":{"rendered":"https:\/\/www.cambridge.org\/core\/blog\/?p=64369"},"modified":"2025-11-06T11:57:23","modified_gmt":"2025-11-06T11:57:23","slug":"hybrid-parasites-detecting-admixture-between-species-genomes","status":"publish","type":"post","link":"https:\/\/www.cambridge.org\/core\/blog\/2025\/09\/18\/hybrid-parasites-detecting-admixture-between-species-genomes\/","title":{"rendered":"Hybrid Parasites: detecting\u00a0admixture between species genomes"},"content":{"rendered":"
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New research<\/a> uncovers how two marine nematode parasites are interbreeding, in a contact area of their range of distribution<\/h4>\n\n\n\n
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The latest Paper of the Month is, Hybridization and introgression of the mitochondrial genome between the two species Anisakis pegreffii and A. simplex (s.s.) using a wide genotyping approach: evolutionary and ecological implications<\/em><\/strong><\/a>, and is available open access in Parasitology<\/a><\/em><\/strong>.<\/p>\n<\/blockquote>\n\n\n\n

Why look at hybrid parasites?<\/strong>
In the natural world, species don\u2019t always stay neatly separated. Sometimes, when their paths cross, they can interbreed. This process \u2014 called hybridization<\/strong> \u2014 is surprisingly common and may play a role in evolution.<\/p>\n\n\n\n

For parasites, it\u2019s especially interesting. When different species mix, their offspring may pick up unusual mixed traits. They might spread in new ways, become harder (or easier) for hosts to resist, or even change the risk they pose to  humans.<\/p>\n\n\n\n

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That\u2019s exactly what scientists found happening in the waters off southern Spain. In the Atlantic and the Alboran Sea, two worm-like parasite species \u2014 Anisakis pegreffii<\/em> and Anisakis simplex (s.s.)<\/em>\u2014 often become adult worms in the same marine mammal host, and where their geographical ranges overlap, they don\u2019t just share host space and condition\u2026 they sometimes cross-breed.<\/p>\n<\/div>

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How do you spot a hybrid parasite?<\/strong>
From the outside, hybrids look just like their parents. So, scientists turn to genetics \u2014 like looking at the parasite\u2019s DNA \u201cfingerprint.\u201d<\/p>\n\n\n\n

In this study, researchers used a set of powerful genetic tools to compare parasites from the contact zone with those from elsewhere. By checking across many different points in the genome, they could spot which individuals were pure parental species and which were hybrids \u2014 even picking out first-generation crosses versus \u201cbackcrosses\u201d (hybrids that had bred again with one of the parental species).<\/p>\n\n\n\n

Think of it as detective work: every parasite carried a mix of genetic clues revealing who its parents were.<\/p>\n\n\n\n

What did the scientists discover?<\/strong>
The results were fascinating:<\/p>\n\n\n\n