Wednesday, August 20, 2008

Gotta Love Blue

As I get ready for the beginning of school next week I am still thinking about what my emphasis will be. I am enrolled in a Bachelor's degree program at Boise State in Biology with an emphasis in Ecology, but I must still choose a taxonomy focus of my ecology work. The choices include Entomology, Ornithology, Vertebrate Natural History, Mammalogy, or Aquatic Entomology.  I might take more than one.  The likely choices include Ornithology (birds) or Mammalogy, although my recent fascination with parasites could influence this.

I have started to monitor the new research coming out in these areas looking for interesting papers. This will help me understand what the research is like and what I might be most interested in. This has been aided by the fact that I now have online access to a very large selection of scientific journals through the university library.  One of the many perks of being a student, free bus passes being another!

I have found a few papers on interesting topics, but some have been way over my head. One interesting Ornithology paper I found in Behavioral Ecology and Sociobiology is titled Maternal investment in eggs is affected by male feet colour and breeding conditions in the blue-footed booby, Sula nebouxii.

Dentressangle, F., Boeck, L., Torres, R. (2008). Maternal investment in eggs is affected by male feet colour and breeding conditions in the blue-footed booby, Sula nebouxii. Behavioral Ecology and Sociobiology DOI: 10.1007/s00265-008-0620-6

The research builds on previous research regarding a female's ability to manipulate the resource investment in eggs when the health of her mate is in question. Reproduction requires a significant investment in resources.  It was hypothesized that if a female knew that her mate's health was in question, that she might decrease the investment in subsequent egg production. In blue-footed boobies the male helps to feed the chicks.  If the male were not to survive, or his health was declining due to lack of food, then the chicks survival would be in question. Decreasing resource commitment to a second egg could increase the survival rate of the first egg.  This seems like a reasonable hypothesis, but does the female observe this and does she have the physiology to control the resource investment in subsequent eggs?

The study tracked many mating pairs of blue-footed boobies in two separate years, one with good breeding conditions and one with poor breed conditions. They captured males from each of the experimental pairs within 24 hours of the first egg being laid and painted their feet to decrease the brightness (11.18% decrease in maximum reflectance and 46.4% decrease in total reflectance). The decrease in brightness was still within the natural color ranges of blue-footed boobies. They also established a control population with no color modification in the male's feet. The study then tracked the egg size, egg density, yolk androstenedione and testosterone and compared the experimental group against the control group.

The results were significant.  Female boobies whose mates had duller colored feet decreased egg size, decreased egg volume, and delayed the laying of the second egg as compared to the control group.  The androgens and testosterone were not statistically affected (although breeding conditions year to year did have a significant effect).

All three factors are believed to affect the survivability of the chicks. Smaller, low density eggs have a lower chance of hatching. The smaller size and the delay in the second egg will make any chicks that do hatch less competitive with the first chick from the brood, giving the first chick an advantage and the second a disadvantage. This likely increases the chance that in poor conditions that at least one chick (the first) will survive.

I found this a very interesting study which opens the door for even further research - does this truly increase survivability of the first chick (evolution would indicate that it is highly likely), which other environmental factors have an effect, how common is this among other species of birds, etc.

Maybe Ornithology should be my focus. I'll have to find a Mammalogy paper to balance this out...

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TheChadwick said...

If you're at BSU-- then I'd recommend Ornithology... more specifically Raptor bio as that seems to be what most of the faculty are good at and they have a masters degree in it if you're so inclined (one of the few masters degrees they offer in the sciences).

wolf21m said...

TheChadwick, Thanks for the info. Yes, I looked into that degree but I do not yet have the undergraduate requirements, so starting with a BS in Biology is my first step. I hope to take Ornithology next semester.