def filter_dose_by_individual_species(doses, species):
    """Filter out relevent doses by the species name

    If it does find doses with the specific species name, it returns a list of these.
    If it doesn't find any doses with the specific species name, it returns None.

    :param doses: A list of dose objects
    :type list:

    :param species:
    :type string:

    :returns: either None or a list of dose objects
    """

    relevant_doses = []

    for dose in doses:
        if dose.individual_species.species_name == species.species_name:
            relevant_doses.append(dose)

    return relevant_doses