physiology

 

Promiscuity Breeds Efficiency: Mouse Mating Systems Affect Sperm Sprints

Posted 17 August 2014 by Anne-Marie Hodge

Sperm is constant joke-fodder. From the opening credits of the movie "Look Who's Talking" to various Shakespeare passages, we humans never seem to tire of laughing at hordes of competitive little sperm powering past each other in the race towards their final destination. They're unbelievably tiny, simple entities, and yet the outcome of their performance is huge. Or perhaps we just stay fascinated by the dramatic fact that all of our lives began when one of those little guys won a race that has been going on since... Read more

Stress Promotes Skin-Healing in Mice

Posted 10 August 2014 by Anne-Marie Hodge

Everyone has experienced the effects of stress: fidgeting, sweating, inability to focus, gain or loss of appetite, racing heartbeat, and so on. All of these things can happen to us when the adrenal system releases "stress hormones," a process that often disrupts many aspects of daily life. We don't like it. Our aversion to stress has sparked a cottage industry of self-help books, seminars, podcasts, videos, and various therapies that claim to teach us how to chill out and stay calm.   Although the "symptoms" of stress make... Read more

Does Sloth Fur Fungus Hold the Next “Wonder Drug?”

Posted 28 January 2014 by Anne-Marie Hodge

Throughout human history, humans have included wild animals in their folklore, mythology, and daily vocabulary. Animals with especially distinctive traits have likewise become ensconced in modern popular culture and language. Leonine features are considered striking and sexy, outfoxing someone is a demonstration of cleverness, and it is obnoxious to parrot someone in a conversation. Being slothful is unlikely to gain you any respect. Sloths spend the vast majority of their lives nearly sedentary, moving through the canopy at incremental paces.... Read more

Life in the slow lane: Primate metabolisms run at half the pace of other mammals

Posted 22 January 2014 by Anne-Marie Hodge

  Western society is obsessed with metabolism. Magazines bombard us with splashy headlines offering hyperbolic advice on how to boost, rev, fire up, jump-start, enhance, or otherwise maximize our metabolic rates. You should eat six meals a day, or fast two days a week, or drink green tea before every meal, or sleep 9 hours a night, or hang upside down, or use company X’s proprietary powder/capsule/plant-extract to ensure that your metabolism is purring along like a jet. We are... Read more

Parasite-Swapping Between Two Introduced Species: The Cane Toad Strikes Again

Posted 10 September 2013 by Anne-Marie Hodge

  Aliens are among us, and they don't have to come in the form of little green humanoids to cause problems. Non-native species create major headaches, whether they are introduced intentionally or arrive at far-flung places as stowaways. These "alien" invasive plants and animals can (and often do) wreak havoc on native species, because local organisms often lack the adaptations to deal with a novel predator and/or competitor to which they've never before been exposed. Entire ecosystems have been disrupted... Read more

The Case of the Heterodox Fox: Bergmann’s Rule North and South of the Equator

Posted 11 August 2013 by Anne-Marie Hodge

Ecology is a mind-bogglingly complex field. As such, ecologists make few "rules"--they're more like "tentative tenets." Nature presents an exception for nearly everything, so even "rules" are often framed less as absolute laws and more as hypotheses to continue testing. One of the best-known "rules" of evolutionary ecology, is Bergmann’s rule, which predicts that endothermic animals found in cooler climates will have larger body sizes than conspecific populations or closely-related species in warmer habitats (Bergmann 1847). Bergmann’s reasoning was that... Read more

Hibernating Bears Run Hotter and Cleaner While Pregnant

Posted 3 August 2013 by Anne-Marie Hodge

When it comes to feats of physiology, bears are among the superstars of the mammalian world. Their endurance is legendary. During hibernation, bears regularly survive up to six full months without consuming any food at all. Hibernating bears reduce their heart rates by over 80% and decrease their metabolic rates by 50-75%, yet they actually remain conscious during this time (Laske et al. 2010; Tøien et al. 2011). Bears also manage to avoid muscle atrophy and loss of bone density,... Read more

‘Dead’beat Dads: First Evidence of Posthumous Reproduction

Posted 16 July 2013 by Anne-Marie Hodge

All organisms have an evolutionary imperative to maximize the number of offspring they produce. We work within a finite lifespan to successfully pass on as many genes as possible, however: so many gametes, so little time. Some strategy must be involved, right? Given the inescapable time constraints, many aspects of animal social structure are centered around producing as many healthy offspring as possible during a lifetime. From butterflies surviving only one month to elephants that live for sixty years, every... Read more

Brains Versus Brawn Amongst Wild Canids

Posted 8 April 2013 by Anne-Marie Hodge

Continuing the theme from my last post, I'm going to cover a new study involving some of the carnivores that I'm observing and studying out here in Kenya. Last time we talked about mongoose, and this time we'll move on to one of my favorite mammalian families: the Canidae. Few things are more important for a carnivore's survival than having a lethal bite. The critical mechanics underlying bite force have significantly influenced carnivore evolution--they determine morphology, hunting behavior, and prey... Read more

How do “fish of a feather” shoal together?

Posted 8 February 2013 by Anne-Marie Hodge

“Birds of a feather flock together,” as the old saying goes, and that simple axiom raises many fascinating questions. Do animals really choose to associate with conspecifics that closely resemble themselves? If so, how do they even determine, without the either aid of mirrors or cognitive abilities that enable self-recognition, who is “of a feather” and who is not? Why would once choose to be “just a face in the crowd,” or even a member of a crowd at all?... Read more