evolution – Page 11 – Shamskm: A site to exchange knowledge and solutions

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…)

Ancient Dinosaur Nursery Oldest Nesting Site Yet Found

By Guest PostJanuary 27, 2012Scienceadam yates, cretaceous periods, david evans, dinosaur eggs, dinosaur footprint, dinosaur nesting site, dinosaur record, dinosaur reproduction, early dinosaur, early jurassic period, eric roberts, evolution, evolutionary history, excavation, fossil record, hans-dieter sues, hatchling, jurassic, massospondylus, oldest known embryo, prosauropod dinosaur, reproductive behaviour, robert reisz, royal ontario museum, sauropods, sedimentary rocks, smithsonian institute, South Africa

*UTM professor unearths fossils in South Africa*

An excavation at a site in South Africa has unearthed the 190-million-year-old dinosaur nesting site of the prosauropod dinosaur Massospondylus-revealing significant clues about the evolution of complex reproductive behaviour in early dinosaurs. The newly unearthed dinosaur nesting ground predates previously known nesting sites by 100 million years, according to study authors.

A new study led by University of Toronto Mississauga paleontologist Robert Reisz, with co-author, Professor David Evans of ecology and evolutionary biology and the Royal Ontario Museum, along with a group of international researchers, describes clutches of eggs, many with embryos, as well as tiny dinosaur footprints, providing the oldest known evidence that the hatchlings remained at the nesting site long enough to at least double in size. (more…)

Babies Are Born With “Intuitive Physics” Knowledge, Says MU Researcher

By Guest PostJanuary 26, 2012Scienceevolution, glass of milk, hidden objects, infants, intuitive physics, knowledge, kristy vanmarle, natural interaction, northwestern university, predict the future, skill, susan hespos, university of missouri, unsupported objects

*Numerous infant studies indicate environmental knowledge is present soon after birth*

COLUMBIA, Mo. – While it may appear that infants are helpless creatures that only blink, eat, cry and sleep, one University of Missouri researcher says that studies indicate infant brains come equipped with knowledge of “intuitive physics.”

“In the MU Developmental Cognition Lab, we study infant knowledge of the world by measuring a child’s gaze when presented with different scenarios,” said Kristy vanMarle, an assistant professor in the Department of Psychological Sciences in the College of Arts and Science. “We believe that infants are born with expectations about the objects around them, even though that knowledge is a skill that’s never been taught. As the child develops, this knowledge is refined and eventually leads to the abilities we use as adults.” (more…)

English Literature Influenced Prize-Winning Paleontologist

By Guest PostJanuary 14, 2012Science21st century, age of reptiles, ancient plant structure, carbon cycle, carboniferous period, cocktail party, dinosaurs, earth, ecology, evolution, excalibur movie, fieldwork, fossil record, giant fungus, harvard university, history of life, ice age, jung eun lee, kevin boyce, knowledge, la brea tar pits, lloyd degrane, los angeles, macroevolution, mammal fossils, michael foote, million years ago, mural, pair of calipers, paleontology, plant fossils, prehistoric life, scanning electron microscope, school, soil moisture, terrestrial ecosystems, vascular plants

For a short time in grade school, Kevin Boyce lived within two blocks of the La Brea tar pits in Los Angeles, a place where ice age mammal fossils had been discovered. Above his bed hung a poster of the Yale Peabody Museum’s famous Age of Reptiles mural. But it wasn’t a boyhood fascination with prehistoric life that influenced his interest in paleontology, but rather the medieval literary world of Chaucer that Boyce discovered in college.

“I didn’t think twice about fossils between the ages of 7 and 20,” said Boyce, associate professor in geophysical sciences. Even during his undergraduate studies in literature and biology at the California Institute of Technology in the early 1990s, the deep history of life on Earth was far from his mind. (more…)

Evolution is Written All Over Your Face

By Guest PostJanuary 11, 2012Scienceevolution, evolutionary detectives, faces of primates, facial expressions, facial features, new world primates, shaping human faces

Why are the faces of primates so dramatically different from one another?

UCLA biologists working as “evolutionary detectives” studied the faces of 129 adult male primates from Central and South America, and they offer some answers in research published today, Jan. 11, in the early online edition of the journal Proceedings of the Royal Society B. The faces they studied evolved over at least 24 million years, they report. (more…)

50-Million-Year-Old Cricket and Katydid Fossils From Colorado Hint at Origin of Insect Hearing

By Guest PostJanuary 7, 2012Nature, Science50 million year old, abdomens, chorus of crickets, colorado, crickets and katydids, crucial survival advantage, dena smith, eardrum, evidence of ears, evolution, fossil evidence, fossil insect, front legs, grasshoppers, green river formation, green river fossils, lacewings, lake deposits, modern insects, museum, paleontologist, roy plotnick, tachinid fly, utah, wyoming

*The team scoured more than 500 museum drawers of Green River fossils for crickets and katydids with intact front legs, looking for evidence of ears.*

How did insects get their hearing? A new study of 50-million-year-old cricket and katydid fossils sporting some of the best preserved fossil insect ears described to date are helping to trace the evolution of the insect ear.

According to paleontologist Dena Smith of the University of Colorado Boulder’s Museum of Natural History and University of Illinois Professor Roy Plotnick, who collaborated on the new study at the National Evolutionary Synthesis Center, or NESCent, in Durham, N.C., insects hear with help from some very unusual ears. (more…)

Close Family Ties Keep Microbial Cheaters in Check, Study Finds

By Guest PostDecember 16, 2011Scienceamoebae, Antarctica, canopies, clonal lineage, cosmopolitan groups, david queller, deserts, dicty, dictyostelium discoideum, e coli, evolution, forest park, genes, jennie kuzdzal fick, joan strassmann, kissing kin, life cycles, multicellular organisms, mutation, national science foundation, obligate cheaters, sam scheiner, sara fox, single cell, slime mold, social amoeba, st. louis, tropical forests, washington university

*Experiments on “slime mold” explain why almost all multicellular organisms begin life as a single cell*

Any multicellular animal, from a blue whale to a human being, poses a special challenge for evolution.

Most of the cells in its body will die without reproducing; only a privileged few will pass their genes to the next generation.

How could the extreme degree of cooperation required by multicellular existence actually evolve? Why aren’t all creatures unicellular individualists determined to pass on their own genes? (more…)

Predators Drive the Evolution of Poison Dart Frogs’ Skin Patterns

By Guest PostNovember 25, 2011Naturedart frog, evolution, poison dart frogs, poisonous frog, skin patterns

Natural selection has played a role in the development of the many skins patterns of the tiny Ranitomeya imitator poison dart frog, according to a study that will be published in an upcoming edition of American Naturalist by University of Montreal biologist Mathieu Chouteau. The researcher’s methodology was rather unusual: on three occasions over three days, at two different sites, Chouteau investigated the number of attacks that had been made on fake frogs, by counting how many times that had been pecked. Those that were attacked the least looked like local frogs, while those that came from another area had obviously been targeted. (more…)

Tag Archives: evolution