BIO_week_4

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Feb 20, 2024

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BIO_weeek_4 What we're talking about This lesson is about competition between members of different species. Last time we talked a little about competition, but it was about members of the same species. The big difference this time is that when we are talking about different species we have to remember that they have different morphologies and physiologies (remember morphology is how something looks and physiology is about function). That may seem obvious. But these differences lead to differences in competitive abilities, which means that competition between different species is often asymmetrical . That means that one member of the pair should be better than the other. We will be reading this lesson from the textbook Chapter 6: Interspecific competition. As usual, do the lesson as you read the text to get the most out of it. You should go subsection by subsection this week - some of the material is very technical. Learning goals By the end of this lesson, you will be able to:  Describe conditions influencing interspecific competition (think of heterogeneity of environments and limiting factors).  Analyze how competition can limit the distributions and abundances of competing species, taking evolution into consideration (think of time to realize niches and develop adaptations)  Illustrate the principle of competitive exclusion , resource partitioning , and character displacement with appropriate examples.  Critically evaluate evidence for interspecific competition as an explanation for the diversity and distribution of species we see today.

Reflections on competition I mentioned in the evolution chapter already that I feel that our society overemphasizes competition over cooperation. Here is a little more on this idea, again, from Anne Buchanan's ecodevoevo blog. " In Mutual Aid: A Factor of Evolution Kropotkin (a Russian scientist, philosopher and anarchist 1848-1921) argues that Darwin was wrong to place so much emphasis on competition, because cooperation -- mutual aid -- is so obviously in evidence all around us. The idea of the struggle for life as a 'law of nature' was something he just couldn't accept because, as he wrote "...I was persuaded that to admit a pitiless inner war for life within each species, and to see in that war a condition of progress, was to admit something which not only had not yet been proved, but also lacked confirmation from direct observation." As a naturalist, Kropotkin spent much time traveling and observing nature. In Mutual Aid he documents evidence of aid over conflict among animals, in humans and throughout human evolution and history, writing: As soon as we study animals -- not in laboratories and museums only, but in the forest and prairie, in the steppe and the mountains -- we at once perceive that though there is an immense amount of warfare and extermination going on amidst various species, and especially amidst various classes of animals, there is, at the same time, as much, or perhaps even more, of mutual support, mutual aid, and mutual defense amidst animals belonging to the same species, or at least to the same society. Sociability is as much a law of nature as mutual struggle . But which comes first, evidence or interpretation?

Kropotkin was a prominent figure in 19th century activist politics. He was, according to the wisdom of the masses, a "geographer, economist, activist, philologist, zoologist, evolutionary theorist, philosopher, writer and prominent anarchist." ( Wikipedia .) He was sympathetic to the plight of the peasant in Russia as a young man, and to socialist ideas, though he eventually settled on anarchism and as a political activist, was imprisoned for subversive activities in 1876. He escaped from prison before his trial, however, and fled to Europe, only returning to Russia after the revolution in 1917, enthusiastic about the changes he saw happening, though eventually disillusioned by the authoritarian socialism that the revolution became. Kropotkin disliked capitalism and the idea that life must be a struggle. As an anarchist, he preferred to believe that humans were capable of mutual aid and cooperation, and that we could effectively run our own societies. On the other hand, competition was in the cultural air when Darwin was doing his thinking, with the British empire dominating much of the world, the beginning of the industrial age and the rise of capitalism, the economics of Thomas Malthus who was so influential to Darwin's thinking, so it was perhaps natural that Darwin, and Wallace too -- and indeed Richard Dawkins in the 1970's -- framed their theories of evolution in terms of competition. One can assert that if Kropotkin was driven by his ideology to see in Nature what his filters allowed him to see, then the same certainly applies to the Darwinians and even to the gentle Charles himself. If Darwin's view prevailed in the west, the cooperation-based views of Lysenko prevailed in the Soviet Union, with disastrous consequences for science. But viewed in its context, these polarities are understandable."

Do you believe that we in the US, as a competitive population, are biased and interpret things as competition, that might not be? Competition is a very powerful force in shaping communities and in affecting natural selection. Competition is also a force which is more obviously seen. Positive interactions between and among species can be less visible. However, over the past few decades, scientists are increasingly recognizing the large impact positive interactions have on organisms at a variety of scales. We will be studying positive interactions in a couple of weeks, however your textbook only devotes half a chapter to these very imporant interactions! So I'm going to sprinkle in some of this theory as we go. I'm not saying only one interaction is the most important in creating the immense biodiversity we see in the world around us. Instead, I want to encourage you to think beyond just the negative interactions as being the most important ones. Textbooks can lag behind contemporary science for various reasons. For me, science is most interesting when we are discovering new ideas, changing old ways of thinking through the collection of evidence, and challenging our beliefs. I know I've said this before, but it's worth repeating: science isn't just a set of facts to be memorized, but rather is a constantly evolving set of ideas based on currently available evidence. As we discussed in week 1, loss of biodiversity can have incredible social and economic costs. Remember the children in Ghana not going to school because of overfishing? Recently, I read an article where a researcher was quoted saying "If spiders disappeared, we would face famine" (Palmer 2014, Washington Post). Or take the economic value of native insects pollinating our food crops: A recent study by Losey and Vaughan put a value of just over $3 billion on the pollination of U.S. fruits and vegetables by native insects. Habitat destruction, degradation, and fragmentation are among the major causes of the decline in biodiversity that we are experiencing. And that also is competition! Our human need for food and housing today competes with the needs of fish, insects, and pandas AND possibly with the needs of future human generations.

Anise swallowtail According to some sources, the second largest cause of the decline in biodiversity are invasive species (see the Asian carp on the left as an example). The ecologist Daniel Simberloff estimates that "of all 1,880 imperiled species in the United States, 49% are endangered because of introduced species alone or because of their impact combined with other forces . " And that, too, is a story about competition - often coined as a war of "invasive" against "native." People's opinions about invasives (or POOPs as they are called, short for "Plant Out Of Place) are divided. The Golden Gate National Parks Conservancy reports that in 2017 over 27,000 volunteers put in more than half a million hours, mostly to combat invasive plants. But on the other side are fierce defenders of maligned species such as eucalyptus and pampas grass, praising not only their intrinsic value but also noting how certain native species have begun to use them. For example, the western anise swallowtail (pictured right) has begun hosting on invasive fennel as well as still laying eggs on a variety of native plants. One study found that butterflies that raise their young on fennel can have an extra reproductive event each year, or two instead of one (Johnson1993). Other factions argue that species extinction is just part of evolution and we should not try to live in a museum, messing with nature and evolution by trying to preserve what

could not keep up. Later this semester, we will be reading about novel ecosystems - or novel assemblages of species that humans have created. People working on these systems recognize that humans have already changed our environment and invasive species aren't going to be completely eradicated and maybe we should be looking at the functioning of these ecosystems, and trying to maximize their functionality. What is the science that both sides quote? Is it a fair battle? What is fair anyway? Theories of POOP's lead to some very interesting discussions which we will get back to later in the semester. Let's turn to the basics first...  Losey, J.E., and M. Vaughan. 2006. The economic value of ecological services provided by insects. BioScience 56(4): 311- 323.  National Parks Conservancy. Annual report 2015. https://issuu.com/parks-conservancy/docs/2015-annual-report. accessed 2/2016  Brian Palmer. Why spiders may be the human race's ultimate spin doctors. The Guardian.<http://www.theguardian.com/environment/2014/aug/01/spiders-conservation-importance-agriculture>.  https://eeb.utk.edu/people/daniel-simberloff/.  https://www.ncbi.nlm.nih.gov/pubmed/28564889 Crash course community ecology The Khan Academy video gives you a nice introduction to the main concepts about competition. Download the questions for this video. Scan them, and as you watch this episode of crash course ecology, stop the video to jot down answers. The video is relevant to this chapter until 8:50 min. You do not need to turn in the answers to these questions - they are to help you study . Source: Khan Academy. Community Ecology: Feel the Love. https://www.youtube.com/watch?v=GxE1SSqbSn4 NOTE: All Khan Academy content is available for free at < www.khanacademy.org >". Used under the Creative Commons license.

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