2011-16_Coad - EVOLUTION (11:704-486) COADAPTATION SMOUSE...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
EVOLUTION (11:704-486) COADAPTATION S MOUSE – SPRING 2011 1 A a B b C c D d E e F f G g H h C OADAPTATION Biotic Interactions: Many adaptations for a given species are responses to other species, and how the two species interact. Viewed from the perspective of a focal species, looking outward, they can be classified broadly as: (a) resources (food or habitat), (b) competitors, (c) enemies (predators, parasites, etc.), (d) commensals (co-livers), and (e) mutualists (mutual advantage). Coevolution – The point here is that other organisms are part of the environment for our focal species, but more interesting is the thought that our focal organism can evolve, in response to other organisms, but can also drive the evolution in those other organisms. The possibility of reciprocal evolutionary pressure between the players has probably contributed importantly to the development of biodiversity on the planet, over the last 3.5 billion years. Elaboration – Coevolution can take several forms: (a) arms race, as with the wolf and the deer, faster wolves representing a selective force for faster deer, and vice versa ; (b) diffuse coevolution, where a response to one organism is also a response to others; (c) coordinated radiation and speciation, where radiation in both lineages is highly correlated. Phylogenetic Perspective – There are different ways that species can evolve in association. The first is uninterrupted association/concordant divergence, where the two lineages have been locked together from the beginning. The second is by colonization, so that there has been some lateral transfer. Futuyma gives two examples: The bacterium Buchnera is always associated with aphids, and the two phylogenies, that of Buchnera and that of aphids, are coordinate. The two organisms are obligate symbiots, and Buchnera is passed vertically through the aphid’s eggs. They are inextricably locked together, and it would seem that the two have been associated for ~ 250 million years. The 2 nd example involves the bacterium Wolbachia , whose phylogeny indicates that it can switch arthropod hosts periodically. Its phylogeny and that of the arthropods it parasitizes are not coordinate, because the bacteria can spread laterally. The pattern is thus: Aphid Phylogeny Buchnera Phylogeny
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
EVOLUTION (11:704-486) COADAPTATION S MOUSE – SPRING 2011 2 Enemies and Victims – Imagine an organism (H) which is eaten by another (P). It is obviously to the advantage of H not to be eaten and to the advantage of P to be able to eat H. Both are under evolutionary pressure, the host to avoid being eaten and the predator to do the eating. There are four things that can happen: (a) an arms race, where each is evolving to overcome the changes in the other, endlessly, (b) a polymorphism in each, representing a sort of balance, (c) continual cycles of compensating advantage, and (d) extinction of one or the other. All of these have formal models, describing the dynamics, as well as myriad examples.
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 08/18/2011 for the course ECOLOGY 301 taught by Professor Staff during the Spring '11 term at Rutgers.

Page1 / 6

2011-16_Coad - EVOLUTION (11:704-486) COADAPTATION SMOUSE...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online