<p>The concept of biological fitness is foundational
for our understanding of both ecology and evolution. Fitness is often described
vaguely as an organism’s contribution to the next generation. The reason this
is vague is because researchers define and measure fitness differently across
fields. I suggest that the myriad definitions and ways
to measure fitness commonly employed have led to debates and, seemingly
contradictory results. In order to investigate the use of the concept of
fitness, I performed a literature review and asked, (1) How is biological fitness
defined and used by researchers? (2) How is fitness actually measured by
researchers? To address these questions, I surveyed 478 papers published between
2012 and 2016, that included the word ‘fitness’ in the title, and were in the
Web of Science categories of ‘ecology’ and ‘evolutionary biology’. In my
analysis of the journal articles fitness was only defined 33% of the time. Among
studies that did explicitly define fitness, I categorized 18 different
definitions, though only 7 were found in more than 5% of papers. I also found differences in how fitness was
measured. I found 87 measurements that I grouped into 13 categories. In
addition to my survey of the literature, I performed an experiment to explore
the relationship between different measures of fitness. Vegetative biomass and
reproductive biomass are often both used as metrics of fitness by plant
ecologists. In this experiment I determined the relationship between two
popular measures of plant fitness vegetative biomass and reproductive yield. I found that these two proxies for plant
fitness, vegetative biomass and reproduction, were unimodally related, meaning:
1) intermediate sized plants have the greatest reproductive output, and; 2) for
any unique amount of reproduction there is both a small and a large plant with
identical reproductive output. Two things emerge from the literature review and
the experiment: first, given the many definitions that exist, researchers
should be clear about which one they are using. Second, one must be clear about
the expected relationship between proxy measurements and fitness, as it may be
complex, or non-existent.</p><p></p>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/9107930 |
| Date | 15 August 2019 |
| Creators | Mariah L Mobley (7042775) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/Biological_Fitness_A_Discussion_of_Definintions_and_Metrics/9107930 |
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