... even if you think the gambit might win you some votes!
Monday, October 20, 2008
Thursday, October 9, 2008
Loss of Diversity
So where does this leave us? Rosenzweig acknowledges that due to the reality of human population needs large productive areas of landscape may not be able to be set aside solely for wildlife. He proposes a new paradigm of comprise he terms Reconciliation Ecology, which he describes as the modification of human habits and habitats to accommodate species diversity. His solutions often require complex relationships between government, business and the private sector. While, when possible, conservation of land for wildlife is often the best solution Reconciliation Ecology provides a new framework to increase habitat that is accessible to both humans and other species. Accordingly, this would provide larger habitat ranges for species, which, in turn, would cause a decrease in the loss of speciation.
Rosenzweig sees this as a win/win solution, which happens to be part of the title of one of his books on the topic. While some might argue, myself included, that it seems more like a win for us and a lose, although less of one, for wildlife. Many environmentalists, and others, want more and more lands set aside for pure conservation and see Reconciliation Ecology as a sell out. I can see their reasoning, however, I also think they may be missing an important point. The key word in his proposal is “compromise”. I believe he intended his idea would be a way that would take land that humans need for whatever purpose and try to make as many accommodations we can to allow it to be somewhat useful habitat. Those areas would most likely not be available for traditional conservation. That being said, I think the label sell out doesn’t quite fit, however, I’m not sure I would call it a win/win solution either.
M. L. Rosenzweig (2001). Loss of speciation rate will impoverish future diversity Proceedings of the National Academy of Sciences, 98 (10), 5404-5410 DOI: 10.1073/pnas.101092798
Of squirrels and conifers coevolving
The feeding preferences of pine squirrels (Tamiasciurus) on conifers lead to two separate patterns of evolution; one of divergence and one of convergence. Squirrels first forage indiscriminately, and then switch to discriminate feeding when supplies run short. This causes selective pressure on the species that is least easily used and results in divergence (Smith, 1970). This selection also produces a divergence between the two tree species in regards to defense mechanisms, such as early shedding of seeds. An example of convergence results, when part of the prey is temporarily inaccessible to the squirrels, thus resulting in energy withheld. Squirrels tend to feed the most on individual trees that are different from the rest in that they are producing more cones, or more seeds per cones (Smith 1970).
Another study, explored other information of populations of red squirrels Tamiasciurus, and found that they are territorial. An individual will have its specific area that it maintains year-round. The individual will forage in autumn to assemble a cache of food items. The cache will be located near the center of the individuals’ territory (Larsen et al, 1997). During periods of shortage, squirrels depend on cached food (Vander Wall, 1990). The squirrels will leave their midden to forage on their territory only if the environment happens to be milder on that particular day (Larsen et al, 1997). The squirrels are then foraging the cones that still remain on the trees. Unfortunately, winter foraging does have some drawbacks. It may be more energetically costly to forage than to feed on the food already stored in their midden. It also increases the risk of predation (Larsen et al, 1997).
A study conducted by Lindsay inadvertently tested Smith’s hypothesis about squirrel size relative to cone morphology or cone anatomy. More specifically, Lindsay tested whether squirrel size was influenced by pressure in maintaining efficiency within foraging for a cone cache. He observed that changes in cone morphology selected for squirrel size (Lindsay, 1986). Small squirrels were found in areas dominated by spruce, hemlock, and redwoods (all of which have small cones with little energy per cone). Conversely, large squirrels were found in forests that had larger cones with a greater energy per cone (Lindsay, 1986). His study showed that discriminatory feeding tactics based on the individuals’ size could minimize loss of energy from the food source as they became more efficient in handling time. Efficiency, was calculated by measuring the amount of energy in a particular food while taking into consideration the energy used to process the food. This relationship is noted by Palmer, who expressed the total energy as “net energy” with the energy lost in processing known as “handling time.” Thus, minimizing handling time is a highly efficient tactic for feeding discrimination and efficiency (Palmer, 1981). This is particularly applicable to squirrels, because they need to obtain lots of energy to store up for winter; they need to be efficient in their foraging techniques in order to survive.
Lindsay noted more evidence in support of Smith’s research by observing T. douglasii in association with small cones. This makes sense as douglasii has weak jaw muscles and can manipulate the smaller cones. T. hudsonicus was found in association with large, thick cones, suitable for hudsonicus as it has strong jaw muscles (Larsen, 1986).
I found Smith’s experiment to be exceptionally thorough. This is evident by many authors who have cited Smith’s work within their own studies. However, he was unable to discern if any animal was exerting a selection pressure to maintain thick seed coats (as a defense mechanism by the conifers). I have not yet found an article exploring this important topic. More research needs to be conducted to discover if insects or birds are inhibited by the thick seed coats of ponderosa pine, western white pine, and Douglas-fir (Smith, 1970). If animals are selectively choosing seeds with a thinner coat, then they are creating a selective pressure for the conifers to produce a thicker seed coat in order to escape predation.
References:
K. W. Larsen, C. D. Becker, S. Boutin, M. Blower (1997). Effects of Hoard Manipulations on Life History and Reproductive Success of Female Red Squirrels (Tamiasciurus hudsonicus). Journal of Mammalogy, 78 (1), 192-203
S. L. Lindsay (1986). Geographic size variation in Tamiasciurus douglasii: Significance in relation to conifer cone morphology Journal of Mammalogy, 67 (2), 317-325
E. L. Mowat (1960). No serotinous cones on central Oregon lodgepole pine Journal of Forestry, 58, 118-119
A. Richard Palmer (1981). Predator Errors, Foraging in Unpredictable Environments and Risk: The Consequences of Prey Variation in Handling Time Versus Net Energy The American Naturalist, 118 (6), 908-915 DOI: 10.1086/283883
Christopher C. Smith (1970). The Coevolution of Pine Squirrels (Tamiasciurus) and Conifers Ecological Monographs, 40 (3), 349-371 DOI: 10.2307/1942287
Wall, V. 1990. Food hoarding in animals. University of Chicago Press.
Friday, October 3, 2008
Seminar today on the evolutionary ecology of becoming urban
Its my own turn at bat in our departmental colloquium today. Here's the blurb on what I'll talk about:
Becoming urban: behavioral and evolutionary implications of living in the city
Dr. Madhusudan Katti, Department of Biology, California State University, Fresno
Abstract
On: Friday, October 3, 2008, At: 3:00-4:00 PM, In: Science II, Room 109
Thursday, October 2, 2008
Darwin Quote of the Day
"I had, also, during many years followed a golden rule, namely, that whenever a published fact, a new observation or thought came across me, which was opposed to my general results, to make a memorandum of it without fail and at once; for I had found by experience that such facts and thoughts were far more apt to escape from the memory than favourable ones. Owing to this habit, very few objections were raised against my views which I had not at least noticed and attempted to answer."
-- Charles Darwin, in Darwin, Francis ed. 1887. The life and letters of Charles Darwin, including an autobiographical chapter. vol. 1. London: John Murray.
Wednesday, October 1, 2008
Carl Zimmer on a career among the Galapagos finches
Thanks, Carl!
Tomorrow, I dine with a rationalist!
Yes, I am one of the group of faculty members invited to a reception with James Randi tomorrow night, before he gives his public lecture on campus. Here's the announcement:
The University Lecture Series
Proudly Presents
James Randi
“Pseudo-Technology in the New Millennium”
Thursday, October 2, 2008
7:30 p.m. ~ Satellite Student Union
James Randi has an international reputation as a magician and escape artist, but today he is best known as the world’s most tireless investigator and demystifier of paranormal and pseudoscientific claims. He has pursued “psychic” spoonbenders and exposed the dirty tricks of faith healers. He appears frequently on US television shows and in the late 1960’s was host of “The Randi Show” on WOR-Radio.
To read more about James Randi visit our website
For Ticket Information: please call the University Student Union Information Center at 278-2078 or visit them in the University Student Union.
Carnivals new and old
It seems a new forthnightly carnival focused on evolution has been going around for the past month, and I only just noticed. Well, you can start by reading The Carnival of Evolution #3 at Greg Laden's blog.
And, btw, the venerable Tangled Bank is also online in its 115th incarnation at Evolved and Rational. Check it out.
And students, don't tell me you can't find inspiration to write something about evolution here!
Zotero: an open source alternative to Endnote
If you haven't tried the campus site-licensed Endnote software to manage your reference collection yet - (or perhaps because you have and didn't like it) and if you'd prefer an open-source alternative with some apparently nifty online features (esp. for firefox users), consider Kevin Zelnio's advice: Screw EndNote, Try Zotero. You can download it here.
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