z97-238.chp:Corel VENTURA
نویسنده
چکیده
Six songbird species were studied to determine how testis size varies in relation to latitude, using data from breeding areas at latitudes 7°N to 69°N. Three of the species (Carpodacus mexicanus, Vireo olivaceus, Geothylpis trichas) exhibited a significant positive relationship, one (Passerculus sandwichensis) a significant negative relationship, and two (Agelaius phoeniceus, Spizella passerina) no significant association between relative testis mass and latitude. These results suggest that sperm competition may also vary latitudinally, likely in response to geographic variation in breeding season length, extrapair mating intensity, and social mating system. Résumé : Six espŁces doiseaux chanteurs ont ØtØ ØtudiØes dans des territoires de reproduction entre les latitudes 7°N et 69°N pour dØterminer la relation entre la taille des testicules et la latitude. Chez trois des espŁces (Carpodacus mexicanus, Vireo olivaceus, Geothylpis trichas), il y a une relation positive significative entre la masse relative des testicules et la latitude, chez une autre espŁce (Passerculus sandwichensis), la relation est nØgative et significative et chez deux autres (Agelaius phoeniceus, Spizella passerina), il ny a pas de relation entre les deux variables. Ces rØsultats semblent indiquer que la compØtition entre les spermatozoïdes peut Øgalement varier selon la latitude, probablement en rØaction à la variation gØographique de la durØe de la saison de reproduction, de lintensitØ des appariements hors couple et du systŁme social
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