Evolution of Armor Plating in Three-spined Sticklebacks EEB 440: Biology of Fish Isaac Fine, Allie...
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Transcript of Evolution of Armor Plating in Three-spined Sticklebacks EEB 440: Biology of Fish Isaac Fine, Allie...
Evolution of Armor Plating in Three-
spined Sticklebacks
EEB 440: Biology of Fish Isaac Fine, Allie Leitch, Karen Baweja,
Meagan Crofoot
Three Spined SticklebackGasterosteus aculeatus
• Frequent the Northern Hemisphere• Typically 4-6cm 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 Benefitsof Armor Loss
• 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 Benefitsof Armor Loss
• Marine three-spined sticklebacks rely on their full armor plating to protect them from predators
• It is not uncommon for freshwater sticklebacks to have fewer spines because of the decreased amount of predators (Smith 2009).
• 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
Life history
Review
• Amount of Lateral plate armor is heritable and under selection
(Bell 2001)
• Major Locus o Ectodysplasin-Eda
(Colosimo et al. 2005)
• Minor Locio 5o 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)
• Model Organism: an extensively studied species used to help understand the biological processes of other species.
• quick generation time• rapid evolution• ability to adapt to new environments• well studied
Applications
• 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)
Lake Washington
• By the 1960s 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
The Great Lakes!
• 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
Conservation Genetics
Future Work
• Speciationo Sexual Selection
Imprinted/Learned Behavior Reproductive Isolation
o Ecological Factors• Model Generation
Future Work
• Sexual Imprintingo Learning mate choice early in life
Paternal Nest Gluingo Know it happens but not the
mechanismo If tied to ecologically divergent traits,
sexual isolation
Future Work
• Stickleback exampleso Body Size
Foraging niche dependanto 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?