Tuesday, January 16, 2007
Body Size, Performance and Fitness in Galapagos Marine Iguanas
Integrative and Comparative Biology 2003 43(3):376-386; doi:10.1093/icb/43.3.376
Martin Wikelski and L. Michael Romero
Complex organismal traits such as body size are influenced by innumerable selective pressures, making the prediction of evolutionary trajectories for those traits difficult. A potentially powerful way to predict fitness in natural systems is to study the composite response of individuals in terms of performance measures, such as foraging or reproductive performance. Once key performance measures are identified in this top-down approach, we can determine the underlying physiological mechanisms and gain predictive power over long-term evolutionary processes. Here we use marine iguanas as a model system where body size differs by more than one order of magnitude between island populations. We identified foraging efficiency as the main performance measure that constrains body size. Mechanistically, foraging performance is determined by food pasture height and the thermal environment, influencing intake and digestion. Stress hormones may be a flexible way of influencing an individual's response to low-food situations that may be caused by high population density, famines, or anthropogenic disturbances like oil spills. Reproductive performance, on the other hand, increases with body size and is mediated by higher survival of larger hatchlings from larger females and increased mating success of larger males. Reproductive performance of males may be adjusted via plastic hormonal feedback mechanisms that allow individuals to assess their social rank annually within the current population size structure. When integrated, these data suggest that reproductive performance favors increased body size (influenced by reproductive hormones), with an overall limit imposed by foraging performance (influenced by stress hormones). Based on our mechanistic understanding of individual performances we predicted an evolutionary increase in maximum body size caused by global warming trends. We support this prediction using specimens collected during 1905. We also show in a common-garden experiment that body size may have a genetic component in iguanids. This 'performance paradigm' allows predictions about adaptive evolution in natural populations. [Galapagos Islands]
-------
Recent post: Why are lions not as big as elephants?
Technorati: integrative, comparative, biology, complex, organismal, traits, body, size, evolutionary, fitness, natural, systems, performance, foraging, reproductive, marine, iguanas, island, stress, hormones, global warming, trends, specimens, genetic, adaptive, evolution, galapagos, islands, lions, elephants
Add to: CiteUlike | Connotea | Del.icio.us | Digg | Furl | Newsvine | Reddit | Yahoo
And then this cell must live long enough to reproduce.
And then the reproduced cell must live long enough to do the same.
And then more "accidents" must happen to cause more complexity.
And then more "accidents" must happen to cause more complexity.
And long before the first "accident" evolution is nothing but a silly, mystical fairy tale.
: 10:37 PM, July 09, 2008 What you see above is the nail in the coffin for the Darwinian evolutionary theory. A recent email from an evolutionist said " I am asking you to not look around at all the different species now present, but for the fun of it go back to a time when a simple cell miscodes and starts a new direction." There is a problem with this, you cannot back to when the cell was simple that time does not exist!! The cell from the very start has been complex and there simply is no evidence that ever shows a time when the cell was anything but complex!
Life in all aspects of it, when properly studied reveals that there is simply nothing simple about life. From the tiniest cell (which by the way you are made up of billions of) to the complex galaxy and even further the universe in which we exist is absolutely, mind blowing, unfathomably complex!! How does this level of complexity arise by chance and left to itself. This the evolutionist simply do not have an answer for.
http://www.icr.org/wisdom-of-God/
Check out this website and realize that we are fearfully and wonderfully made... Psalm 139
Now as I said earlier, there are software’s around us they are for e.g.: The Thoughts and Ideas or the Philosophies that are around us, now consider this all as software’s, but there are Operating Systems also available and they are the Religions that people are in, to understand this things just ask yourself a simple question that is, Why do I believe in what I believe?, Or is their any reason or valid strong reason for it, that I believe in it?.
Today whenever I ask myself these questions I am at peace, because I have so many valid reasons to believe in what I believe. And thanks to HIM that they are not assumptions they are facts, so many people misinterpret
: 3:34 PM, February 12, 2009 : 11:26 PM, April 26, 2009 The evo people'll jump @ you & say no-one believes origins or evol happened by chance but chance + natural selection. They’ll then expound on the latter. What this does is take your eye off chance, your main objection. But the reality is the main engine of creation is still CHANCE. Chance is not a force let alone a creative one. Some say it doesn’t actually exist in nature. It’s a temporary designate for sequencing to which we cannot (as yet) ascribe a law or mechanism; which of course doesn’t mean there isn’t one.
Even if we grant chance the status of reality, odds against a simple protein excede probability bounds of the universe. Roughly, anything whose chance is 1^50 is statistically impossible. Beyond this, there hasn’t been enough time or events since time began. There’s isn’t enough stuff even if the universe was made of bio-raw materials. To believe evolution requires one to take leave of one’s senses.
NATURAL SELECTION: This doesn’t solve anything. It’s NOT a creative force. We could end it there but let’s not be mean. Once stuff's created by SOMETHING ELSE, natural selection does operate. It has however NEVER been observed to produce complexities required. A valid excuse could once be there hasn’t been enough time for observation. This no longer works: There's been plenty of time with microbes since 1859 notwithstanding 30yrs of inducing mutations in fruit-flies.
I think evolution is complete nonsense but I feel alone in today’s society. Anyone felt the same?
Anonymous
I like iguana IS STILL AN IGUANA. How I missed this with finches, moths etc beats me. This is actually ALL the evidence there is.
: 2:56 PM, August 31, 2009 << 'Main Blog' Home
