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Study Finds Significant Skull Differences Between Closely Linked Groups

By Guest PostApril 15, 2012Scienceann ross, ashley humphries, biohistorical context, coimbra, coimbra female, craniofacial characteristic, facial feature, female, female skull, forensic anthropologist, immigrant, intraorbital distance, lisbon, male, male skull, portugal, portuguese women, skeletal remain, skull

In order to accurately identify skulls as male or female, forensic anthropologists need to have a good understanding of how the characteristics of male and female skulls differ between populations. A new study from North Carolina State University shows that these differences can be significant, even between populations that are geographically close to one another.

The researchers looked at the skulls of 27 women and 28 men who died in Lisbon, Portugal, between 1880 and 1975. They also evaluated the skulls of 40 women and 39 men who died between 1895 and 1903 in the rural area of Coimbra, just over 120 miles north of Lisbon. (more…)

A Bug’s (Sex) Life: Diving Beetles Offer Clues About Sexual Selection

By Guest PostFebruary 6, 2012Nature, Sciencearizona desert, co evolution, dawn higginson, diving beetles, dytiscidae, epifluorescence image, Europe, evolution, evolutionary relationship, female, fertilization, great diving beetle, hygrotus sayi, invertebrate, kari segraves, kelly miller, larva, male, mammal, mollusk, reproductive organ, scott pitnick, sexual evolution, sexual selection, sexual trait, speciation, sperm evolution, sperm storage, spermatheca, syracuse university, thermonectus marmoratus, university of arizona

*Studies of diving beetles suggest sperm evolution may be driven by changes in female reproductive organs, challenging the paradigm of post-mating sexual selection being driven mostly by competition among sperm.*

Studying female reproductive tracts and sperm in diving beetles (Dytiscidae), researchers from the University of Arizona and Syracuse University have obtained a glimpse into a bizarre and amazing world of sperm that can take on a variety of forms – including joining together into conglomerates that navigate the twisted mazes of the female reproductive tract.

Analyses of the evolutionary relationships among diving beetles reveal that sperm form appears to follow function dictated by female reproductive organs. (more…)

Monogamous Birds….Peeping on the Neighbours!

By Guest PostJanuary 28, 2012Naturecolourful plumage, courtship dance, disease, dominique drullion, female, female zebra finche, frederique dubois, hypothesis, immunosuppressive effect, laboratory, male bird, male genetic quality, monogamous species, public information, reproduction period, sexual selection, social environment, song, testosterone, zebra finch

It is well documented that male birds seduce females using their songs, colourful plumage and courtship dances. These signals reflect male genetic quality and will be graded by the female to determine a male’s potential as a mate. The stronger the grade, the better the odds of being selected.

But this basic rule isn’t the only yardstick used by females. As surprising as it seems, birds know how to use data from their social environment to maximize their chances of reproduction. Frédérique Dubois, a professor at the Université de Montréal Department of Biological Sciences, has already demonstrated that female Zebra Finches will favour a male chosen by another female. Dubois refers to this as imitation and the use of “public information” in choosing a mate. (more…)

The Genetics of Self-Incompatibility

By Guest PostNovember 6, 2010Nature, Scienceantigens, female, fertilization, genes, genetic, immune response, inbreeding, male, offspring, organism, petunia, petunia pistil, petunia pollen, plant, pollen, proteins, rna, rna-destroying enzyme, seiji takayama, sexual organs, t-cell receptors, teh-hui kao

*Petunias show that the mechanisms behind inbreeding prevention are similar to immune response*

About the image: The female part of the petunia flower secretes an enzyme that is designed to deter pollen tube growth, thereby preventing fertilization. However, in the cases that the pollen has come from a genetically different plant, the pollen produces its own protein that combats the pistil’s enzyme. With the enzyme out of the way, the pollen tube can keep growing and fertilization can occur. Image credit: Zina Deretsky, National Science Foundation

Inbreeding is a bad strategy for any organism, producing weak and problematic offspring. So imagine the challenge of inbreeding prevention in a plant where male and female sexual organs grow right next to each other! Such is the genetic conundrum faced by the petunia. (more…)

Tag Archives: female

Study Finds Significant Skull Differences Between Closely Linked Groups

A Bug’s (Sex) Life: Diving Beetles Offer Clues About Sexual Selection

Monogamous Birds….Peeping on the Neighbours!

The Genetics of Self-Incompatibility