the tortoise and the hare an overview of life history
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The tortoise and the hare an overview of life history. An organism’s life history is the suite of traits that define its growth, develop, and (most importantly) reproductive activity. - PowerPoint PPT PresentationTRANSCRIPT
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The tortoise and the hare an overview of life history
![Page 2: The tortoise and the hare an overview of life history](https://reader035.vdocuments.us/reader035/viewer/2022070419/56815b8e550346895dc99173/html5/thumbnails/2.jpg)
An organism’s life history is the suite of traits that define its growth, develop, and (most importantly) reproductive activity.
![Page 3: The tortoise and the hare an overview of life history](https://reader035.vdocuments.us/reader035/viewer/2022070419/56815b8e550346895dc99173/html5/thumbnails/3.jpg)
Sexual reproduction usually involves parts that can be identified as “male” and “female”. In most animals, individuals usually have a recognizable gender. Plants often defy gender concepts.
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Reproduction generally results in substantial energetic cost
“Switching” in plants: Allocation of resources to either growth or reproduction
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Reproductive output is related to size of the parent organism
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Reproductive output is influenced by access to resources
Access to resources is determined largely by- 1) habitat
-optimal habitat = more resources, more offspring-marginal habitat = fewer resources, fewer offspring
2) competition- competition with others reduces access to resources- less competition = more offspring
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An organism’s life history is the suite of traits that define its growth, develop, and (most importantly) reproductive activity.
• Ecologists, traditionally, refer to life history “strategies.”
• Life history strategies were then classified these into two very broad categories.
K-selected species have long life spans, low reproductive rates, are often slow growing. Slow and steady wins the race
r-selected species are fast growing, with high reproductive rates. They arrive at reproductive maturity very quickly. Live fast and die young
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Some features of the “K strategy”
1) Long life span2) Low reproductive rate3) High investment in offspring
• Large seeds• Post-partum attention by parents
4) Low dispersal rates (sometimes)5) Slow growth
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Some features of the “r strategy”
1) Short life span2) High reproductive rate3) Low investment in offspring
• Small seeds• Little post-partum attention by parents (your on your own kid!!)
4) Long dispersal distances5) Rapid growth
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Organismal life histories span a spectrum of possibilities
• K and r, (and just described) are typical of the endpoints.
• Most of the real world is somewhere in between.
• Many species are a blend of each strategy (some trees grow fast, but live a very long time, with long-distance seed dispersal).
• Many population ecologists are irritated by the r – K concept because they over simplify.
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Bristlecone & dandelionan overview of life history