The ART of mating : alternative reproductive tactics and mating success in a nest-guarding fish

Fish use different modalities to access mates for reproduction, often referred to as Alternative Reproductive Tactics (ARTs). ARTs are an example of coexisting phenotypes, which have to hold some degree of reproductive success to persist in a population. In the Mediterranean damselfish (Chromis chromis), territorial males colonise nests on rocky reefs, competing for females, while sneaker males attempt to parasitically spawn in those nests. Here we combine behavioural observations in the field with molecular analyses, using bi-parentally and maternally inherited markers, to investigate reproductive success patterns of the two observed male ARTs in terms of number of eggs sired and number of females contributing to each nest. Cuckoldry was observed in every nest sampled, with at least two and up to seven sneakers per nest; however, the nesting male always significantly fathered the large majority of the eggs (on average 49%) in each clutch. Each sneaker fathered around 7% of the clutch. The average number of females whose eggs were fertilised by nesting males was 6.76 (ranging 2-13), while each sneaker on average fertilised the eggs of 1.74 (range 1-8) females. Using this sibship reconstruction, we investigated some of the factors involved in the regulation of the dynamic equilibrium of reproductive success between the two ARTs showed by C. chromis males. Our results show that the sneakers’ reproductive success was positively linked to egg clutch size; the density of individuals in the nesting area negatively affected the size of egg clutches; the rate of defence behaviours performed by nesting males negatively influenced the number of females contributing to each nest

Changing expendable bathythermograph fall rates and their impact on estimates of thermosteric sea level rise

A time-varying warm bias in the global XBT data archive is demonstrated to be largely due to changes in the fall rate of XBT probes likely associated with small manufacturing changes at the factory. Deep-reaching XBTs have a different fall rate history than shallow XBTs. Fall rates were fastest in the early 1970s, reached a minimum between 1975 and 1985, reached another maximum in the late 1980s and early 1990s, and have been declining since. Field XBT/CTD intercomparisons and a pseudoprofile technique based on satellite altimetry largely confirm this time history. A global correction is presented and applied to estimates of the thermosteric component of sea level rise. The XBT fall rate minimum from 1975 to 1985 appears as a 10-yr “warm period” in the global ocean in thermosteric sea level and heat content estimates using uncorrected data. Upon correction, the thermosteric sea level curve has reduced decadal variability and a larger, steadier long-term trend

Quality control cookbook for XBT data

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