An interest of this blog is why Gray Wolves and Coyotes do not hybridize in nature but Eastern Wolves(Red Wolves) and Coyotes(both western and eastern) will and do hybridize.....................So when I came across the article below about how our two species of Woodrat(Desert and Bryant's) largely do not hybridize even when they live in close contact with each other,I wanted to see what was different between the canids and rats as it related to hybridization proclivity............... I found it interesting to note that Mating opportunities between the two woodrat species are limited because they each have their homes and forage in very distinct habitats, even though those habitats are right next to each other................Also discovered is that the desert woodrat females were intimidated by Bryant's woodrat males due to their larger body size and aggressive nature............. In contrast, Bryant's females, themselves larger, were open to mating with the smaller, more docile desert woodrat males as well as the males of their own species.................Finally, the offspring of woodrat hybridization had higher infant mortality than did the infants of "purebred" rats of either species..................Gray Wolves historically see Western Coyotes as competitors and seek to kill or drive off the Coyotes....................Eastern Wolves(Red Wolves) are viewed to be descended from an ancient Coyote lineage and when these Wolves are in small numbers and in fractured populations, the males will gladly mate with both Western and Eastern Coyotes.......And it seems that the offspring of Eastern Wolf/Coyote matings are anything but fragile,,,,,,,,,,in fact seemingly better suited to the altered habitat conditions of our Eastern landscape environment......It will be interesting to see in future years if hybridization dynamics are accelerated by warming temperatures( their likely impact on forest and field habitat conditions)----------------For more on wolf/coyote hybridization information, go to the first page of my blog and in the SEARCH BOX type in "wolf/coyote hybridization and eastern wolf/coyote hybridization)

HOW WOODRATS  LARGELY KEEP TO TWO SPECIES WHERE SOME CANID SPECIES READILY HYBRIDIZE
URL: ScienceDaily

Two new studies from the Wildlife Conservation Society, Idaho State University, and the University of Nevada Reno look at the surprising variety of factors that prevent two closely related species of woodrats from becoming a single hybrid species despite the existence of hybrid individuals where the two species come into contact.

After finding that two closely related species, the desert and Bryant's woodrats, could interbreed and produce hybrid offspring, scientists set out to determine why only 14 percent of the population in a "contact zone" had genetic signatures from both species. (If the two species were similar enough to interbreed, what was keeping them from merging into a single hybrid species?)

In the study, "Ecological segregation in a small mammal hybrid zone: Habitat-specific mating opportunities and selection against hybrids restrict gene flow on a fine spatial scale," which appears in the March print edition of the journal Evolution, the authors discuss the factors driving these mating dynamics in a hybrid zone in southern California.

DESERT WOODRAT

Trapping and handling hundreds of woodrats (also known as packrats), the scientists found that the two species are highly associated with different habitat types, though they may live within meters of each other along the boundary. Their research showed that 98 percent of Bryant's woodrats occupied a boulder-strewn hillside made up of coastal / Sierra vegetation, while 93 percent of the desert woodrats occupied the adjacent valley floor consisting of Mojave desert scrub and a sandy substrate. This, in spite of the fact that both habitats were theoretically available to both species.

"Mating opportunities between species are limited because the two species make their homes and forage in very distinct habitats, even though those habitats are right next to each other," said lead author of both studies, Quinn Shurtliff of the Wildlife Conservation Society and Idaho State University.

Gray Wolves do not hybridize with Coyotes and will look to drive them out of their habitat

Another reason why interbreeding between species is limited: personality conflicts. The scientists brought wild-caught woodrats into the laboratory to test female mate preferences.

They found that Bryant's woodrat females selected either Bryant's woodrat males or desert woodrat males with equal preference. Desert woodrat females, however, almost always mated with males of their own species.

The reason? The desert woodrat females were intimidated by Bryant's woodrat males due to their larger body size and aggressive nature. In contrast, Bryant's females, themselves larger, were open to mating with the smaller, more docile desert woodrat males as well as the males of their own species.

Western Coyotes do not hybridize with Gray Wolves but will do so with Eastern Wolves

Another factor shown to be determining the number of hybrids is that hybrid offspring do not survive to adulthood as well as do the other two species. Higher proportions of Bryant's woodrats survived to their first year of adulthood than did the hybrids (33 percent vs. 10 percent). The same was the case for the desert woodrats (22 percent vs.10 percent percent). Once the hybrids reached their first year of adulthood, however, they fared as well as the purebreds.

The reason for the low juvenile hybrid survivability, the authors say, may lie in the lack of aggressiveness and ability to compete with purebred males for denning sites and in winning territorial battles. This may necessitate greater dispersal for the male hybrids pushing them out of range of female hybrids and exposing them to greater predation pressure.

BRYANT'S WOODRAT

Shurtliff said, "These studies offer further insight into the behavioral and ecological dynamics of hybrid zones. Understanding these unique areas is important because there are many examples of naturally occurring hybrid zones, and new hybrid zones will form in the future as climate change and human impacts cause species distributions to shift and come into contact. For example, scientists have documented hybrid zones between introduced and native species, and climate change has already been linked to hybridization among flying squirrels in eastern North America. It is important to understand these relationships so that we can predict, and where necessary, mitigate their negative impacts."

Eastern(Red Wolves) will hybridize with both Western and Eastern Coyotes

"Experimental evidence for asymmetric mate preference and aggression: behavioral interactions in a woodrat (Neotoma) hybrid zone," appears online on BioMed Central.Authors include: Quinn R. Shurtliff of the Wildlife Conservation Society; Peter J. Murphy and Marjorie D. Matocq of the University of Nevada, Reno; and Jaclyn D. Yeiter of Idaho State University.

"Ecological segregation in a small mammal hybrid zone: Habitat-specific mating opportunities and selection against hybrids restrict gene flow on a fine spatial scale," appears in the March print edition of the journal Evolution. Authors include: Quinn R. Shurtliff of the Wildlife Conservation Society; Peter J. Murphy and Marjorie D. Matocq of the University of Nevada, Reno.

Eastern Coyotes will hybridize with Eastern(Red Wolves)

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Story Source:

The above story is based on materials provided by Wildlife Conservation Society.Note: Materials may be edited for content and length.