DOI: 10.5061/dryad.mw6m905x9
title: Ecological and behavioural drivers of offspring size in marine teleost fishes

description: Aim: Our aim was to evaluate the role of ecological and
 life-history factors in shaping global variation in offspring size in a
 marine clade with a diverse range of parental care behaviours.
 Location: Global. Time period: Data sourced from
 literature published from 1953 until 2019. Major taxa
 studied: Marine teleost fishes. Methods: We compiled a
 species-level dataset of egg and hatchling size for 1,639 species of
 marine fish across 45 orders. We used Bayesian phylogenetic mixed models
 to evaluate the relationship between offspring size and environmental
 factors (i.e., mean temperature, chlorophyll-a and dissolved oxygen
 content together with their annual variation), as well as latitude,
 reproductive strategy, parental body size and fecundity. We also tested
 long-standing hypotheses about the co-evolution of offspring size and the
 presence of parental care in BayesTraits. Results: After
 controlling for parental body size and phylogenetic history, we find that
 increased egg size is associated with colder and oxygen-rich waters, while
 hatch size further depends on food supply and the reproductive strategy
 exhibited by the species. Irrespective of the initial investment in egg
 size, species with parental care or demersal egg development yield larger
 hatchlings compared to pelagic spawners. We also demonstrate that hatch
 size has co-evolved with advanced forms of care in association with
 parental body but fail to find a relationship with other types of care.
 Main conclusions: Our study shows that parental care behaviours,
 together with environmental context, influence the evolution of classic
 life-history trade-offs on a global scale. While the initial investment in
 eggs is driven primarily by temperature and oxygen content,
 hatchling size also reflects the impact of care an offspring has received
 throughout development. In support of the ‘offspring-first’ hypothesis, we
 find that an increase in hatch size drives the evolution of advanced care
 provision. 
description: Dataset
 includes two proxies for offspring size – egg size and larval size at
 hatching – as well as taxonomic information, parental body size,
 reproductive strategy, caregiver identity, fecundity, latitude of species
 range midpoint and a set of environmental variables characterising each
 species' range (please see the main manuscript and Supporting
 Information Methods S1 for further details). Main sources of information
 included global and regional datasets, larval guides, online databases and
 family-level reviews; please see the Reference List to Supplementary Data
 for further details. For consistency, we attempted where possible to score
 both offspring proxies from the same source. The information was collected
 primarily from secondary sources (see above), but we also consulted the
 primary research articles referenced in the secondary literature in cases
 where only one proxy for offspring size was available. These instances
 have been marked up in the References columns (e.g., ‘Ref Egg Size’) in
 the Supplementary Dataset using the following format: [reference to
 primary source] in [reference to secondary source]. As an additional step,
 we performed an automated search in Web of Science using search terms
 ‘repro*’/ ‘egg*’/ ‘larva*’/ ‘care*’/ ‘early life’/ ‘life history’/
 ‘spawn*’ in combination with a genus name to identify sources of
 information in cases where the reproductive strategy for some species
 within the genus with known offspring size was uncertain or unobserved;
 asterisks (*) denote multiple possible suffixes.