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Evolução dos cuidados parentais e da parentalidade em peixes ósseos da subclasse actinopterygii : uma abordagem filogenética
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Advisor(s)
Abstract(s)
Os cuidados parentais referem-se ao investimento pós-fertilização realizado pelo(s)
progenitor(es), que possibilita o aumento da sobrevivência e do sucesso reprodutor dos
descendentes, enquanto a parentalidade diz respeito ao(s) sexo(s) cuidador(es). A subclasse
Actinopterygii exibe considerável diversidade de comportamentos parentais, encontrando-se
igualmente presentes todas as formas de parentalidade. Os estudos filogenéticos da evolução
dos cuidados parentais são escassos, assentando alguns na parentalidade, com resultados
contraditórios entre estudos. A abordagem filogenética actual consiste no mapeamento de
caracteres em filogenias, através da associação dos estados dos caracteres aos taxa terminais,
permitindo a reconstituição histórica da evolução dos caracteres, mediante a utilização de
"software" adequado (e.g., Mesquite). Foram conduzidos alguns mapeamentos de cuidados
parentais e de parentalidade em filogenias aos níveis da família e do género, tal como foi
mapeada a parentalidade numa filogenia da subclasse Actinopterygii, não sendo porém
conhecido à escala global nenhum estudo de mapeamento de cuidados parentais.
A presente dissertação pretendeu, através do mapeamento de caracteres, testar um
conjunto de hipóteses, de acordo com as quais, a guarda evoluiu da ausência de cuidados
parentais e originou independentemente a incubação oral e o transporte externo de ovos, tendo
a parentalidade evoluído direccionalmente através da sequência de transições «ausência de
parentalidade, uniparentalidade masculina, biparentalidade, uniparentalidade feminina» (i.e.,
modelo "stepping-stone"). Foi recolhida e compilada informação respeitante aos cuidados
parentais e à parentalidade numa base de dados compreendendo 389 famílias. Da análise da
base de dados, constatou-se a presença de cuidados parentais em 23,9 % das famílias
amostradas, nas quais a guarda e a uniparentalidade masculina constituíram as formas
predominantes de cuidados parentais e de parentalidade, respectivamente. Os caracteres em
estudo foram mapeados em três filogenias moleculares, incidindo nos seguintes taxa: coorte
Osteoglossomorpha, ordem Siluriformes e subclasse Actinopterygii. Na subclasse em estudo,
os cuidados parentais e a parentalidade evoluíram de ancestrais sem cuidados parentais nem
parentalidade. Ao nível global, a transição do estado ancestral para a guarda, bem como a
transição do estado ancestral para a uniparentalidade masculina foram as mais observadas,
tendo as restantes registado ocorrências minoritárias. Relativamente à evolução dos cuidados
parentais, os dados apoiaram a origem da incubação oral na guarda, ao passo que o transporte
externo de ovos evoluiu da guarda e directamente do estado ancestral, sugerindo a não
existência de um padrão evolutivo único. No que diz respeito à evolução da parentalidade, os
dados não apoiaram o modelo stepping-stone, não tendo sido observada a sequência predita
completa. Apenas foram registadas cinco a sete sequências transicionais «estado ancestral,
uniparentalidade masculina, biparentalidade», não tendo sido apoiada a assunção da
biparentalidade como estado intermédio entre a uniparentalidade masculina e a
uniparentalidade feminina. Adicionalmente, a evolução da parentalidade revelou uma
diversidade de transições entre estados superior àquela observada na evolução dos cuidados
parentais, sugerindo a não existência de um padrão sequencial evolutivo único aplicável à
subclasse Actinopterygii. A congruência, geralmente observada, entre estados inferidos de
cuidados parentais e de parentalidade para as famílias não documentadas sugeriu o interesse
do mapeamento de caracteres no fornecimento de dados relativos a estas famílias.
Parental care refers to the form of post-fertilization investment that enhances survival and reproductive success of caregiver’s progeny, while parenting concerns the caregiver’s sex. Actinopterygian fishes display considerable diversity of parental behaviors, and include all forms of parenting. Phylogenetic studies on the evolution of parental care are scarce; some of them were based on the caregiver's sex, and have produced conflicting results among studies. The current phylogenetic approach consists of mapping characters on phylogenies, by associating character states to terminal taxa, which allows the historical reconstruction of character evolution, by using appropriate software (e.g., Mesquite). Few studies tracing parental care and parenting traits on phylogenies at the family and genus level were conducted; parenting categories were traced upon a phylogeny of the subclass Actinopterygii; conversely, parental care states were not mapped at the subclass level. The present dissertation aimed to test a suite of hypotheses, by performing character mapping. According to the aforementioned hypotheses, guarding behavior evolved from the absence of parental care and independently originated mouthbrooding and external egg carrying, whereas parenting traits experienced a directional evolution, through the transitional sequence «no parenting, uniparental male care, biparental care, uniparental female care» (i.e., stepping-stone model). Character information was retrieved and compiled into a database encompassing 389 actinopterygian families. The database analyses revealed the incidence of parental care and parenting in 23.9 % of the sampled families; also, in families displaying parental care, guarding and male-only care were recorded as prevailing forms of parental care and parenting, respectively. The study characters were traced on three molecular phylogenies concerning the following taxa: cohort Osteoglossomorpha, order Siluriformes and subclass Actinopterygii. In this subclass, parental care and parenting traits evolved from ancestors devoid of parental care or parenting. At the global level, the transition from the ancestral state to guarding, and that from the ancestral state to uniparental male care were the most observed ones, whereas the remaining transitions recorded low scores. Concerning the evolution of parental care, the data supported the evolution of mouthbrooding from guarding, whilst external egg carrying arose from both guarding and the ancestral state, which suggested the absence of a unique evolutionary pattern. Regarding the evolution of caregiver's sex, the data did not support the stepping-stone model, since the complete predicted sequence was not observed. Only five to seven transitional sequences «no parenting, uniparental male care, biparental care» were recorded; consequently, the data did not corroborate the assumption that biparental care is an intermediate state between male-only and female-only care. In addition, the evolution of caregiver's sex showed higher diversity of transitions among states than that recorded in the evolution of parental care, suggesting the absence of a unique evolutionary pattern fitting the entire subclass. The overall congruence between inferred states of parental care and parenting for undocumented families suggested the interest of character mapping, in order to provide data regarding these families.
Parental care refers to the form of post-fertilization investment that enhances survival and reproductive success of caregiver’s progeny, while parenting concerns the caregiver’s sex. Actinopterygian fishes display considerable diversity of parental behaviors, and include all forms of parenting. Phylogenetic studies on the evolution of parental care are scarce; some of them were based on the caregiver's sex, and have produced conflicting results among studies. The current phylogenetic approach consists of mapping characters on phylogenies, by associating character states to terminal taxa, which allows the historical reconstruction of character evolution, by using appropriate software (e.g., Mesquite). Few studies tracing parental care and parenting traits on phylogenies at the family and genus level were conducted; parenting categories were traced upon a phylogeny of the subclass Actinopterygii; conversely, parental care states were not mapped at the subclass level. The present dissertation aimed to test a suite of hypotheses, by performing character mapping. According to the aforementioned hypotheses, guarding behavior evolved from the absence of parental care and independently originated mouthbrooding and external egg carrying, whereas parenting traits experienced a directional evolution, through the transitional sequence «no parenting, uniparental male care, biparental care, uniparental female care» (i.e., stepping-stone model). Character information was retrieved and compiled into a database encompassing 389 actinopterygian families. The database analyses revealed the incidence of parental care and parenting in 23.9 % of the sampled families; also, in families displaying parental care, guarding and male-only care were recorded as prevailing forms of parental care and parenting, respectively. The study characters were traced on three molecular phylogenies concerning the following taxa: cohort Osteoglossomorpha, order Siluriformes and subclass Actinopterygii. In this subclass, parental care and parenting traits evolved from ancestors devoid of parental care or parenting. At the global level, the transition from the ancestral state to guarding, and that from the ancestral state to uniparental male care were the most observed ones, whereas the remaining transitions recorded low scores. Concerning the evolution of parental care, the data supported the evolution of mouthbrooding from guarding, whilst external egg carrying arose from both guarding and the ancestral state, which suggested the absence of a unique evolutionary pattern. Regarding the evolution of caregiver's sex, the data did not support the stepping-stone model, since the complete predicted sequence was not observed. Only five to seven transitional sequences «no parenting, uniparental male care, biparental care» were recorded; consequently, the data did not corroborate the assumption that biparental care is an intermediate state between male-only and female-only care. In addition, the evolution of caregiver's sex showed higher diversity of transitions among states than that recorded in the evolution of parental care, suggesting the absence of a unique evolutionary pattern fitting the entire subclass. The overall congruence between inferred states of parental care and parenting for undocumented families suggested the interest of character mapping, in order to provide data regarding these families.
Description
Tese apresentada para cumprimento dos requisitos
necessários à obtenção do grau de Doutor em Biologia do
Comportamento apresentada no ISPA – Instituto Universitário no ano de 2020
Keywords
Actinopterygii Cuidados parentais Parentalidade Mapeamento de caracteres Parental care Parenting Character mapping