The author assumes that because parthenogenesis has not been proven to occur in mammals, that it does not occur in mammals. This is flawed because it’s possible parthenogenesis. does occur in mammals, even if it hasn’t yet been proven.

The author states that parthenogenesis is known to occur in a “wide variety” of nonmammal vertebrates. That doesn’t mean the author believes parthenogenesis ocurs in “all” nonmammalian vertebrates.

The author doesn’t point to an alternate explanation of parthenogenesis. Also, the issue is whether parthenogenesis occurs in mammals, not what explains the phenomenon of parthenogenesis.

There are no necessary or sufficient conditions for parthenogenesis described in the premises or the conclusion. So there cannot be a confusion of a necessary condition for parthenogenesis with a sufficient condition.

The claim that the study’s methods were flawed is a premise. We don’t know why the author believes the study’s methods were flawed, so we cannot say the author assumed anything regarding why the studies were flawed.