#sexualdimorphism

[addicted2wasps]

Agaonids are so weird, but awesome! Pleistodontes sp. (Male on left, female on right).

(a.k.a. fig wasps)

[francornerophotography-blog]

American goldfinch (Spinus tristis), male and female in breeding plumage. . . . . . . . . . . . . . . . . . . . . . . #your_best_birds #nuts_about_birds #bestbirdshots #bb_of_ig #kings_birds #bird_brilliance #eye_spy_birds #bns_birds #feather_perfection #birds_adored #pocket_birds #planetbirds #thebirdingsquad #birdsandblooms #birds_illife #sassy_birds #birds_captures #nature_worldwide_birds #ip_birds #total_birds #birdsintheworld_ #raw_birds #sexualdimorphism #goldfinch #birdfreaks #americangoldfinch #best_birds_of_world #raw_allanimals #birds_private (at Daniel Webster Wildlife Sanctuary)

[queenofpaper]

Dragons and Sexual Dimorphism

In the world of Thedas, this is a male dragon:

And this is a mature female dragon:

That is... a very significant size difference.  Phenomenally so.  And yet, we can intuit a few things about dragons from this.  So, to start, what do we know about the dragon life cycle?  Dragons are hatched, roughly deer-sized.  They have high infant mortality.  Female dragons are winged, and when young travel long distances to find a nesting site and territory.   Males are flightless and live out their lives in the caves and territory of a female, hunting for her and caring for her young.

But this isn’t entirely unprecedented in nature either.  This actually most closely mirrors the lifestyle of many spiders: a huge, mostly sedentary female, and tiny roving males.

For example, here is an orb weaver and her tiny suitor.

Spiders are also known cannibals.  One of the reasons male spiders tend to be so much smaller than their counterparts is that it allows them to live longer: a bigger male is more likely to be eaten by a female, and a female is more likely to not bother eating such a tiny meal as that.  The difference between spiders and dragons (besides the obvious) is that dragons are vertebrates and are probably going to engage in sex, while spiders tend to just offer a female spider a small package of sperm for her to use at her leisure.  However, dragons don’t start out huge.  When dragons leave the nest, however, they really aren’t much bigger than the drakes.

I propose that the life cycle of a dragon goes like this:

A dragon is hatched.  After surviving to adolescence, she leaves her mother’s territory, flying in search of a new home far away from drakes she would be related to.  Once she has found it, she attracts young drakes in the area seeking a female, and mates with them, if she doesn’t decide to eat them.  Mating triggers a change in her life cycle, as she ceases to be a roaming creature and settles down into a sedentary life, with her harem of males hunting for her.  She’s also likely capable of storing sperm for later use, a really bizarre thing from a human point of view, since we can’t do it, but incredibly common in the animal world.  Compare this idea to the life cycle of something like a queen bee, who stores the sperm from the drones she mates with (a one-time thing for a drone, since they die right after) and uses it her entire life to produce female worker bees.  Not the males, interestingly.  Sex determination in bees is haploid/diploid, with females (queen and workers both) being a mix of genetic information from their mother and father, two sets of chromosomes (just like we have), and males having only one set of chromosomes from their mother.  Male bees don’t have a father.  Strange but true.

Matings after the high dragon reaches her full size may or may not happen, though I suspect she continues to attract drakes regardless. The drakes, in turn for the protection granted by living in the nest of a high dragon, take a parental role with the dragonlings (as the female’s massive size makes that... tricky).  Female dragons aren’t particularly maternal, I think.  Think of those dragon fights in Inquisition where she’ll just nonchalantly throw her children at you, which always makes me laugh.  As they have no notion of which dragonlings are biologically theirs, and there’s no way for them to tell, it’s in their best interest to care for all the babies equally.

There may be something else, too, to their attraction of drakes, but I think that should be left for another post.

[janesotherstuff]

WEIRD BIRDS; Eclectus parrots

Women are from Venus, Eclectus parrots are from god-knows-where

Lots of bird species have males and females which look so different from one another, it is hard to imagine they even belong to the same social group. But when you see male and female Eclectus parrots sitting side by side, you would be entirely forgiven for thinking they were from different planets. I actually wonder if the birds don’t have to remind themselves of this when they spot a member of the opposite sex wandering along a branch. Indeed, when these parrots were first observed in the wild they were thought to be two distinct species.

The males are a lively lime green with blue wing tips and a bright yellow-orange beak, while the females, whose plumage is a variety of plush burgundies and reds mixed with bright purples, have black beaks. This extreme colour variation between sexes is known as sexual dimorphism. It’s pretty rare for birds of the same species to look this different, and its purpose is quite complicated. Allow me to explain. Eclectus parrots live - like so many of the birds in this blog - in the lush rainforests of New Guinea and surrounding areas. An evolutionary ecologist named Rob Heinsohn spent a lot of time sitting in trees and following these birds to see what they got up to. He also wondered why their colours were so different, and here is what he discovered.

When it comes to nesting time, the female finds herself a hollow in a tree where she stays, brooding her eggs until they hatch. During this time, the male will go and collect food for her. But she won’t just accept food from one male, oh no. She will have several suitors coming to the nest, often at the same time. I know, it’s outrageous. Rob was curious to see how far the males travelled when they foraged, so he decided to follow them in a small aeroplane (because why wouldn’t you have one of those lying around the rainforest?) to see what they got up to. He found that they often flew distances of up to 40 miles to get food. ‘Awww! What a sweet, caring husband that bird is!’ you might think. But hold your horses for one cotton pickin’ minute, because Rob also observed that the males made sneaky visits to other nesting females on their little escapades away from the wife! The scandal! So they’re both at it when the cat’s away! Such loose morals from both parties. I wonder if they have been reading too much Jackie Collins.

But this is all done with serious intentions. Females want to make sure they are well fed, and they do this by letting all the males mate with them in exchange for food. The females are well looked after, and males get to sire the next generation. It’s win-win. 

So what’s up with the colours? Well, when the males fly out to collect food, they spend a lot of time in the open, so being green gives them excellent camouflage against the forest canopy - they need to be able to hide. Females on the other hand, need to be seen - by the males, as well as other females who might be looking for a tree hollow of their own - so their vibrant red and purple colouring stands out like a flag against the tree, as if to say “I’m here! Come feed me!” or “This tree is mine, BACK OFF, lady!”

So there we have it. Dress codes are important, especially when your love life is this complicated.

[texantforimage]

Nor the osteologist

Do I need to make a diaognosis of your sexual diferences from the out side?

[thelegendofawesome]

I just sat for 20 minutes watching a very fat cardinal eat seeds off my porch, while his skinny mate watched from the railing and instead inspected the bird feeder (which I have since unclogged so more seeds come out). I had to draw them finally after watching them for so many months make theirselves at home. Missing my hummingbird friends during this windy winter though! It's fun to notice the differences between these two--it's almost cartoonish. #birds #nature #cardinals #sexualdimorphism #illustration #sketch

[colinpurrington]

Pair of Hawaiian garden spiders (Argiope appensa). Kailua-Kona, Hawai’i./p>

[colinpurrington]

Male and female Hawaiian garden spiders (Argiope appensa). This male was there for at least seven days. Not sure how it will end for him, to be honest. In related species the males are sometimes cannibalized before, during, or after copulation … depending on mood of female. Not very aloha of her. Kailua-Kona, Hawai’i.