Welcome to the DragonflyIssuesInEvolution13 Wiki
Together all participants in Project Dragonfly Issues in Evolution Advanced Seminar in Fall 2013 will contribute words, definitions and explanations to a collaborative wiki. We will use this to advance our understanding of biological evolution and, if we are successful, yours.
Sexual Selection
A process in Natural Selection whereby individual organisms gain a genetic (breeding) advantage by attracting mates. This can occur when males of a species attract more females through successful display behavior (vocalization, demonstrations, or appearance) or through dominance of other males.
On a simpler level, sexual selection occurs whenever an individual chooses a mate according to visual characteristics or even proximity.
Sexual Selection is one of the "Five Fingers of Evolution." You can remember it as the ring finger -- the one that a person wears their wedding ring on to tell everyone they have a mate! (See illustration, right.)
Screencap from the Paul Anderson TED-ed video: The Five Fingers of Evolution
It has been recognized as a powerful agent of evolutionary change, with "far reaching consequences." Sexual selection can influence speciation.
Intrasexual selection as discussed by Freeman & Herron (2007) involves sex to sex combat (for example males fighting males) or fighting over resources (for example a territory) to secure a mate. The opposite sex is not choosing a mate, they mate with the winners. Morphological traits or the use of tactical cleverness are involved with the success of the combat.
Intersexual selection as described by Freeman & Herron (2007) is when an individual chooses a mate based on interactions between two sexes. One example I can think of is the peacock.
Andersson, M. B. (1994). Sexual selection. Princeton University Press.
Freeman, S. & Herron, J. (2007). Evolutionary Analysis 4th Ed. Sexual Selection, pp 401-441.
Natural Selection Tale of the Peacock-0
Sexual Selection & Evolution
YouTube segment of the video "Why Sex" from PBS's Nova Evolution series covering sexual selection and evolution
Lek
lek
1 [lek] Show IPA noun, verb, lekked, lek·king. Animal Behavior . noun
1. A place where males of certain bird or mammal species assemble during breeding season to engage in competitive and territorial displays in order to attract females.
Wikipedia photo of male Great-tailed Grackles on a lek. Photograph by Michael J. Plagens, 2007.
"Lekking" is the gathering of males at a lek site. Behavior associated with lekking often consists of ritualized signals to other males in attempts to display dominance or to females to display fitness for breeding.
Black Grouse Lek
This YouTube video provides a glimpse into a springtime Black Grouse lek in Norway.
Sexual Ornamentation
Sexual ornamentation is a characteristic that attracts a mate or stimulates reproduction. This ornamentation is not limited to morphological features, such as wattles, antlers, color, etc. but may also include song and display, such as male grouses on lekking grounds (Badyaev, 2004) and bugling and urine odor among rutting elk or wapiti. Sexual ornamentation also applies to plants that attract pollinators through the development of flowers (Badyaev, 2004).
Badyaev, A.V. (2004) Developmental perspective on the evolution of sexual ornaments. Evolutionary Ecology Research, 975-991.
Badyaev (2004) discusses the paradox of sexual ornamentation and the costs. A more exaggerated sexual ornament may be accomplished by an increased and more efficient allocation of resources, so that a smaller increase in physical and psychological condition is amplified into a progressively larger sexual ornament. Alternatively, this ornament might be enabled by a decrease in the integration between sexual ornaments and the rest of an organism. It seems that long-growing ornaments better reflect an individual’s condition than ornaments that are shorter growing and less integrated.
Badyaev, A.V. (2004) Developmental perspective on the evolution of sexual ornaments. Evolutionary Ecology Research, 975-991.
Astounding Mating Dance Birds of Paradise -- High Quality
Bird of Paradise for BBC's DVD (posted by Alex Ivanov on Youtube)
Moonwalking Bird HD
Moonwalking manakin! Be sure to watch until the end; especially Michael Jackson fans.