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ADDITIONAL COMPLEXITY. "Many parasite species, however, in addition have asexual multiplication in the first intermediate host and free-living stages actively penetrating the second intermediate host (most digenean trematodes, comprising several thousand species). This alternation between asexual and sexual reproduction may have important consequences for shaping the life cycle." http://onlinelibrary.wiley.com/doi/10.1111/j.1420-9101.2005.00895.x/full View in LinkedIn

PARASITIC COMPLEX LIFESTYLES. "Parasitic helminths comprise an astounding diversity of life cycles, using up to four hosts and a diverse array of transmission modes. A widespread and large group of parasites with a complex life cycle are digenean trematodes. The wide majority of trematodes use three hosts." https://lnkd.in/d7s-kUM View in LinkedIn

PLANT COMPLEX LIFESTYLES. "Complex life styles and alternation of generations are characteristic of many plants, a diploid sporophyte alternating with a haploid gametophyte." http://www.jstor.org/stable/2398799?seq=1#page_scan_tab_contents View in LinkedIn

ELEPHANT IN THE ROOM. "A rather small number of papers...addresses the possible selective advantages or disadvantages of reproducing sexually or asexually, of being haploid or diploid, or of having more than one morphological generation." How is easier to answer for scientists than why. https://lnkd.in/dCDJiTr View in LinkedIn

DIVERSITY AND OPTIONS. "Metazoan life cycles can be complex in different ways. A number of diverse phenotypes and reproductive events can sequentially occur along the cycle, and at certain stages a variety of developmental and reproductive options can be available to the animal, the choice among which depends on a combination of organismal and environmental conditions." https://lnkd.in/dznr758 View in LinkedIn

NOT STATIC SNAPSHOT. "J.T. Bonner (1965) noted that the ultimate description of an organism is that of the life cycle. An organism is not the static representation of the adult we associate with taxonomic characterizations and most ecological theory, but the dynamic unfolding of the genome over ontogeny, and the consequent succession of life history stages or forms." https://lnkd.in/dbkNaGR View in LinkedIn

"ONTOGENY (also ontogenesis or morphogenesis) is the origination and development of an organism, usually from the time of fertilization of the egg to the organism's mature form - although the term can be used to refer to the study of the entirety of an organism's lifespan. Ontogeny is the developmental history of an organism within its own lifetime, as distinct from phylogeny, which refers to the evolutionary history of a species." https://lnkd.in/d6baUsv View in LinkedIn

SO ENDS this first of two weekends contemplating complex life cycles in nature. The bewildering complexity of many life cycles is impressive. Also impressive is how some complex life cycles have simplified during evolution. It is an example of how chance explores as many options as possible in a completely non-linear fashion. Nature is a massive random event generator, and most of her experiments fail. View in LinkedIn

COMPARTMENTS AND TIMING. "Adaptive decoupling could result from developmental compartmentalization, and within such developmental systems, heterochrony could be a route to the deletion of a life cycle phase." http://onlinelibrary.wiley.com/doi/10.2307/2937184/full View in LinkedIn

ADAPTIVE DECOUPLING. "A role of adaptive decoupling is generally supported by comparative data on the relative extent of morphological evolution of larvae and adults and on the frequency of elimination of phases from complex life cycles." http://onlinelibrary.wiley.com/doi/10.2307/2937184/full View in LinkedIn