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Geographic patterns of seed trait variation in an invasive species: how much can close populations differ?

ABSTRACT: Seeds play a major role in plant species persistence and expansion, and therefore they are essential when modeling species dynamics. However, homogeneity in seed traits is generally assumed, underestimating intraspecific trait variability across the geographic space, which might bias species success models. The aim of this study was to evaluate the existence and consequences of interpopulation variability in seed traits of the invasive species Carpobrotus edulis at different geographical scales. We measured seed production, morphology, vigour and longevity of nine populations of C. edulis along the Catalan coast (NE Spain) from three differentiated zones with a human presence gradient. Geographic distances between populations were contrasted against individual and multivariate trait distances to explore trait variation along the territory, evaluating the role of bioclimatic variables and human density of the different zones. The analysis revealed high interpopulation variability that was not explained by geographic distance, as regardless of the little distance between some populations (< 0.5 km), significant differences were found in several seed traits. Seed production, germination, and persistence traits showed the strongest spatial variability up to 6000% of percent trait variability between populations, leading to differentiated C. edulis soil seed bank dynamics at small distances, which may demand differentiated strategies for a cost-effective species management. Seed trait variability was influenced by human density but also bioclimatic conditions, suggesting a potential impact of increased anthropogenic pressure and climate shifts. Geographic interpopulation trait variation should be included in ecological models and will be important for assessing species responses to environmental heterogeneity and change.

SUBMITTER: Fenollosa E

PROVIDER: S-EPMC8292299 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:IntroductionParthenium hysterophorus (Asteraceae) is an invasive weed species that has invaded over 50 countries worldwide. It was first detected in 1980 at Tirat-Zvi, in eastern-northern Israel. In recent years, there has been an increasing concern over the spread of this weed in agricultural and non-agricultural habitats across the country. However, very little is known about the biology of P. hysterophorus and its variation among populations.MethodsSeeds collected from five locations across Israel were germinated and plants were grown in pollen-proof cages under uniform conditions to produce the progeny populations. Spatial parameters, weight and germination under different environmental conditions were recorded for field and progeny populations.ResultsSeeds originating from field populations were significantly smaller and lighter than seeds of the progeny populations. Germination occurred in the range of 10°C to 30°C (To ranges from 19°C to 22.3°C, Tb ranged from 9°C to 15°C, Tc ranged from 24 ℃ to 30.5°C), depending on generation and population. A water potential-based model was developed to estimate germination under different soil water content using specific parameters (b - slope, d - upper limit, e - infliction point). The model suggests a correlation between germination and water potential. Indeed, reduced germination was recorded for the lower water potentials especially for the progeny populations. Spatial parameters, weight and germination under different environmental conditions were recorded for field and progeny populations.DiscussionWe identified differences in seed size and weight, germination under different temperatures, and osmotic potential among P. hysterophorus Israeli populations. Differences across generations may arise due to the transgenerational effects. Our results, may shed light on the germination abilities of P. hysterophorus populations and provide vital insight into understanding the invasive capabilities of this highly noxious weed.