Evolution of Armor Plating in Threespined Sticklebacks EEB
Evolution of Armor Plating in Three-spined Sticklebacks EEB 440: Biology of Fish Isaac Fine, Allie Leitch, Karen Baweja, Meagan Crofoot
Three Spined Stickleback Gasterosteus aculeatus • • Frequent the Northern Hemisphere Typically 4 -6 cm long Have at least 3 dorsal spines Known for their unique trait of Armor Plating
Armor Plating • • Bony Plating in place of scales Existence of the armor plating is dependent on if the fish are marine or freshwater dwellers Marine sticklebacks are typically fully-armored (about 30 bony plates) Freshwater sticklebacks are typically low-armored (about 10 bony plates) (Smith 2009)
Evolutionary Benefits Armor Loss • of When a stickleback gives up body armor, it gains agility and speed o More beneficial in an environment such as a lake o Freshwater environments lack an abundance diversity of predators compared to marine (Smith 2009)
Evolutionary Benefits Armor Loss of
Life history • • Many sticklebacks are anadromous, and the low-armored individuals tend to survive more in the freshwater environments The rate at which this transition occurs is surprising and uncommon: the change can be seen in as little as 1 -3 generations
Review • • • Amount of Lateral plate armor is heritable and under selection (Bell 2001) Major Locus o Ectodysplasin-Eda (Colosimo et al. 2005) Minor Loci o 5 o unnamed o Semi-Additive (Colosimo et al. 2005)
Review Continued • • Additional selection on Eda (Low Armor Allele) o Due to the correlation between decreased armor and increased growth rate § Differences between marine and freshwater sticklebacks (Barrett 2010) Flexible-Stem model of Evolution (Wund et al. 2008)
Applications
Lake Washington • Reverse Evolution: evolving back to a more primitive form resulting in a loss of diversity over time. o Involves the collapse of a phenotypically diverse population into a single form. (Kitano et al. 2008)
The Great Lakes! • • By the 1960 s several Lake Michigan herring species had disappeared, most catches were of a single form. Lake Huron was dominated by 2 herring species in the past, recent data indicate they have become a single hybrid form. Seehausen 2006
Conservation Genetics • • • Humans are playing a huge role in the loss of fish biodiversity Turning natural systems into managed systems leading to homogenous environments o invasive species, overfishing, pollution By using the threespine stickleback to come to a better understanding of these processes we can promote new diversity and prevent future loss in species throughout the world
Future Work • • Speciation o Sexual Selection § Imprinted/Learned Behavior § Reproductive Isolation o Ecological Factors Model Generation
Future Work • Sexual Imprinting o Learning mate choice early in life § Paternal Nest Gluing o Know it happens but not the mechanism o If tied to ecologically divergent traits, sexual isolation
Future Work • Stickleback examples o Body Size § Foraging niche dependant o Nuptial Color § Adaptation to signaling and sensory systems in different light environments o Odor Difference § Diet difference, habitat, and immune system genes determined by local parasites Kozak, Head and Boughman 2011
Questions?
- Slides: 17