Postzygotic Isolation Evolves before Prezygotic Isolation between Fresh and Saltwater Populations of the Rainwater Killifish, Lucania parva

Table 2

Analyses of L. parva survival based on cross type (Pecos, IR, Hybrid) and water chemistry. Results of generalized linear model for (a) proportion of eggs hatched, (b) proportion of fry that survived to 14 days after hatch, (c) total survival (proportion of eggs that survived to 14 days after hatch) in five different water chemistries: reverse osmosis water (RO), soft water (KH3), hard water (KH8), saline (20 ppt), and hypersaline (40 ppt). Statistically significant values are indicated in bold. Number of families per water treatment: RO = 22, KH3 = 25, KH8 = 25, 20 ppt = 25, 40 ppt = 24; total = 121. Number of eggs per water treatment: RO = 220, KH3 = 241, KH8 = 224, 20 ppt = 326, 40 ppt = 241. Number of fry per water treatment: RO = 39, KH3 = 66, KH8 = 44, 20 ppt = 242, 40 ppt = 181.

(a) Proportion of eggs hatched

Source	df	χ ^2	P
Cross	2	18.83	<0.0001
Water Chemistry	4	106.48	<0.0001
Cross * Water Chemistry	8	8.23	0.4116

(b) Proportion of fry survive

Source	df	χ ^2	P
Cross	2	0.64	0.7257
Water Chemistry	4	59.73	<0.0001
Cross * Water Chemistry	8	24.77	0.0017

(c) Total survival

Source	df	χ ^2	P
Cross	2	1.83	0.4013
Water Chemistry	4	77.47	<0.0001
Cross * Water Chemistry	8	19.90	0.0107