Just what the title states. The thought came from reading When has an organism evolved enough to be called a new species?

I'm probably wrong but I understand new species happen sporadically rather than in whole-sale lot during breeding season. Is the new species capable of breeding with members of its parent species? How does a new species survive inbreeding initially?

  • $\begingroup$ I guess you should define "species" first. It`s kinda tricky term and at least in my opinion "child species" overlap with "parent species", "sister species" and so on. $\endgroup$
    – pogibas
    Commented Jul 20, 2013 at 14:11

2 Answers 2


Well, speciation is a process, not a single event thing.

Usually what happens initially is geographic isolation of some members of a species, so in that sense the inbreeding is something that is influencing and you can also think of it as causing the speciation process. The presence of special harmless or semi-harmless disadvantagious mutations - which increases in frequency from this isolation - influences how the species is going to evolve, but eventually shapes this species to better cope adapt to some environment, or evolves the new species out of existence.


This is indeed a very good question, that I have spent a long time thinking about myself. My take on this is that there is indeed a very close relationship between inbreeding and speciation, but that inbreeding actually PRECEDES speciation ! The key to this rather counter-intuitive point of view is that inbreeding actually has several advantages, including that of resulting in cleaner genomes in those offspring that survive inbreeding depression.

In populations that have high degrees of inbreeding, because of, for example, small sizes of populations, or high tendencies to self fertilisation, the recessive mutations that cause inbreeding depression will be progressively eliminated, and there will consequently be very little inbreeding depression.

In such a context, there will thus be no barrier to exploiting other advantages of inbreeding such as reducing the cost of sex, or keeping together advantageous gene combinations. Small groups of individuals would thus be better off breeding among one another than with the ancestral stock, leading to speciation.

If you are interested, or just intrigued, by this kind of concept, I invite you to read the rather long essay I wrote on the subject (The existence of species rests on a metastable equilibrium between inbreeding and outbreeding. An essay on the close relationship between speciation, inbreeding and recessive mutations, Etienne Joly, http://www.biologydirect.com/content/6/1/62 ). And please do not hesitate to get in touch with me directly by email ( atnjoly(at)mac.com ) if you have comments or any further questions after reading this essay.

  • $\begingroup$ Is it possible to divide your post into paragraphs to make it easier to read? $\endgroup$
    – Tomcat
    Commented Aug 7, 2013 at 1:59

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