CrazedEvolutionist

-Hi I am a Master's student in biology. I currently teach college level intro biology courses, and I am currently studying plant evolution. -CrazedEvolutionist

This sounds like group selection. In laymen terms the idea of 'for the good of the species' is a good summation of group selection. There has not been any compelling evidence for group selection being a stronger selection force than natural selection. The gene as the selection unit makes this almost impossible. An example of this would be a group of birds portioning all the food they foraged so each bird receives an equal amount, no matter how much they collected as an individual. But there is a mutation, or learned behavior where one bird decides to eat half of his food before returning to have the food portioned out, that bird would have an advantage over all the other birds and would fair better and leave more offspring. This will always happen in a group selection scenario. Do not get this example confused with kin selection, which explains altruism, which is also explained by the selfish gene theory. This leaves out organisms that can produce by an asexual mechanism. You must also understand that the process of speciation is a continuous process without a clear, distinct line when something becomes a new species. This is true 99.99% of the time, the other 0.01% of the time when speciation is an abrupt process these organisms can reproduce by asexual means.

An alternative to Natural Selection would be something along the lines of inheritance of acquired characteristics, otherwise known as Lamarckism. Inheritance of acquired characteristics was disproved early on, but it was one of the first mechanisms for evolutionary change that was hypothesized. Sexual selection is not really an alternative to natural selection in the meaning of replacing it, but it is an alternative mechanism that can drive evolutionary change. Sexual selection is different than natural selection, because the most fit individual for the environment is not the one that will necessarily leave the most offspring. In the example of the birds of paradise, a male with a shorter tail would be better suited for the environment, in the sense that it could avoid predation longer leading to a longer life, which means it has more chances to have offspring. Instead the female selects a male with a long tail, which makes him less fit for the environment, but he will leave behind more offspring than the short-tailed more fit male. The argument from the good gene hypothesis of sexual selection has only been shown to be true in one paper, so it can't be assumed to be the norm. You might be more entertained by looking at the ideas of different levels of selection. This includes the good gene theory, the unpopular and not strongly supported hypothesis of group selection, and individual selection. It would also be useful for you to understand ideas like kin selection, which is explained by the good gene theory, altruism, and maybe also take a look at evolutionary game theory.